Single-split cage

ABSTRACT

The present invention provides a single-split cage capable of continuously holding a plurality of rolling elements stably for a long time by eliminating the difference in the strength between split regions, by maintaining the strength of the entire cage uniform in the circumferential direction and by maintaining the dimensional accuracy between the split regions constant at the time of molding and also capable of improving load capacity and achieving low cost for assembly. A split section  10  for splitting at one portion in the circumferential direction is formed at regions (split regions  10   a  and  10   b ) extending between pockets  2   p  adjacent to each other in the circumferential direction, engagement sections being engageable with each other are provided at the circumferential central position between the pockets and on a one-side split face Sa and the other-side split face Sb formed by splitting the regions, and in a state in which both the engagement sections are engaged with each other, predetermined clearances are formed between the one-side split face and the other-side split face and between the engagement sections.

TECHNICAL FIELD

The present invention relates to a cage for use in a radial rollerbearing for journaling a rotation system to which a large radial load (aload in the radial direction) is applied as in a power mechanismprovided for automobiles and railroad vehicles, for example, and moreparticularly, to a single-split cage having a circular ring shape andbeing split at one portion in the circumferential direction thereof.Furthermore, the present invention relates to an improvement in asingle-split cage mounted in a needle (needle roller) bearing for use inautomobile transmissions, etc.

BACKGROUND ART

Since a very large load is applied in the radial direction to a rotationsystem in a power mechanism provided for automobiles and railroadvehicles, for example, a radial roller bearing (hereafter referred to asa roller bearing or a bearing) being superior in load capacity for theload has been used conventionally and widely as a bearing for rotatablysupporting the rotation shaft thereof. Such a bearing is equipped withan outer member (for example, an outer ring or a housing beingmaintained in a non-rotating state at all times, or a gear, a roller,etc. being rotatable during use) having a cylindrical outer track on theinner circumferential face thereof, a plurality of rollers (for example,a plurality of needles) incorporated so as to be able to roll betweenthe outer circumferential face (inner track) of an inner member (forexample, an inner ring, a shaft, etc. being rotatable during use)disposed on the inner diameter side of the outer member and the outertrack, and a cage for holding these rollers at predetermined intervals(at equal intervals as an example) in the circumferential direction andmounted on the outer member and the inner member. In addition, the cageis configured so as to be equipped with a pair of circular ring sectionsopposed to each other coaxially with a predetermined clearance providedtherebetween and a plurality of pillar sections for connecting these,for separating the area between the circular ring sections in thecircumferential direction of the circular ring sections and for formingpockets in which the rollers are inserted and held rotatably.

Conventionally, for example, a needle roller bearing (needle bearing) isknown as a bearing capable of being improved in load capacity by virtueof numerous rolling elements (rollers) incorporated while being madecompact. Furthermore, a measure for preventing fretting during bearingrotation is taken for the needle roller bearing, and a single-split cageis applied as an example of the preventive measure in some cases (forexample, refer to Patent documents 1 and 2).

For example, the single-split cage 2 shown in FIG. 25 is equipped with apair of circular ring sections 4 and 6 having a circular ring shape andbeing disposed so as to be opposed to each other and a plurality ofpillar sections 8 continuously extending between the circular ringsections 4 and 6 and arranged at predetermined intervals (for example,at equal intervals) in the circumferential direction. In this case, aplurality of space regions are formed at predetermined intervals (forexample, at equal intervals) in the circumferential direction in theportions enclosed by the pillar sections 8 being adjacent in thecircumferential direction and the pair of circular ring sections 4 and6, and the plurality of space regions are formed as a plurality ofpockets 2 p for rotatably holding rolling elements (rollers), one byone. As a result, in the single-split cage 2, the plurality of rollingelements (rollers) are held at predetermined intervals (for example, atequal intervals) in the circumferential direction.

In the single-split cage 2, the rolling elements (rollers) being held inthe respective pockets 2 p are herein configured as slender rollershaving a small diameter and a length 3 to 10 times the diameter.Furthermore, the single-split cage 2 is, for example, incorporatedbetween inner and outer rings while rotatably holding the rollingelements (rollers) in the respective pockets 2 p, one by one, and, inthis state, revolves along the tracks between the inner and outer ringstogether with the rolling elements (rollers) during bearing rotation.The single-split cage 2 is entirely molded (for example, injectionmolded) with a resin (for example, thermoplastic resin).

Moreover, in the single-split cage 2, a split section for dividing thecage at one portion located in the circumferential direction in adirection being crosswise to (perpendicular to) the circumferentialdirection is provided. The split section 10 is formed in regions(hereafter referred to as split regions 10 a and 10 b) extending betweenthe pockets 2 p being adjacent to each other in the circumferentialdirection, and one-side split face Sa and the other-side split face Sbconfigured by the splitting of the two regions, the split regions 10 aand 10 b, are disposed so as to be opposed to each other in thecircumferential direction. In this case, the pair of circular ringsections 4 and 6 extends, while having a circular ring shape, from theone-side split region 10 a on which the one-side split face Sa is formedto the other-side split region 10 b on which the other-side split faceSb is formed.

Besides, on the one-side split face Sa, a rectangular convex section 12protruding (extending) toward the other-side split face Sb from a partof the central portion thereof is provided; on the other hand, on theother-side split face Sb, a concave section 14 formed by denting a partthereof into a rectangular shape so that the convex section 12 can beinserted therein and engaged therewith is provided. This prevents, forexample, dislocation between the split faces Sa and Sb when thesingle-split cage 2 is incorporated between the inner and outer rings(more specifically, dislocation of the single-split cage 2 revolvingalong the tracks between the inner and outer rings during bearingrotation in the direction of the rotation axis Z of the single-splitcage 2).

Furthermore, Patent document 2 discloses a single-split cage in which aconvex section is provided on one-side split face of the split faces ofthe cage and a concave section is provided on the other-side split faceand the respective end faces thereof are formed into a tapered shape sothat the convex and concave sections having been engaged once are notdisengaged in the circumferential direction.

A case is herein assumed as an example in which a cage for use in abearing having an outer ring as an outer member and a rotation shaft asan inner member is mounted in the inner track portion of the rotationshaft. In this case, the cage is inserted from the end section of therotation shaft and moved to the inner track portion of the shaft in theaxial direction. At the time, in the case that step sections and flangesections having outer diameters larger than the inner diameter of thecage are provided so as to protrude in the outer circumferential rangeof the shaft from the end section of the shaft to the inner track, theinner circumferential section of the cage interferes with these stepsections and flange sections, and the cage cannot be moved to the innertrack portion in the axial direction.

Hence, for the purpose of solving this problem, a configuration of acage in which a part of the cage made of a resin is equipped with asplit section, in other words, a configuration of a cage in which eachof a pair of circular ring sections (rim sections) is formed into adiscontinuous nearly circular ring shape (deficit circular ring shape)having a slit (deficit section) at a part thereof (one position, as anexample) is known conventionally (refer to Patent document 3 and Patentdocument 4). With this kind of configuration, the split section can beexpanded and the cage can be increased in diameter by exerting a forceto the cage in the circumferential direction so that bothcircumferential end faces (the faces opposed to each other at thedeficit section) of the circular ring sections (rim sections) areseparated.

As a result, for example, even in the above-mentioned case that the stepsections and flange sections having outer diameters larger than theinner diameter of the cage are provided so as to protrude in the outercircumferential range of the shaft, when the split section of the cageis expanded (the cage is increased in diameter), the cage can be movedsmoothly to the inner track portion of the rotation shaft in the axialdirection without interfering with the step sections and the flangesections.

Furthermore, after the cage is moved to the inner track portion of therotation shaft, when a force is exerted to the cage so that both endfaces (the opposed faces at the deficit section) of the respectivecircular ring sections (rim sections) in the circumferential directionare brought close to each other in the circumferential direction,whereby the split section is shrunk (returned to its original statebefore expansion) and the diameter of the cage is returned to theoriginal state. Hence, the cage is mounted on the inner track portion ofthe rotation shaft. At the time, a predetermined engagement mechanism isprovided on the opposed faces of the pillar sections adjacent to eachother in the circumferential direction with the split section providedtherebetween so that the split section of the cage is not expandedagain. For example, as such an engagement mechanism, a convex section isprovided on one opposed face so as to protrude toward the other opposedface; furthermore, a concave section is provided on the other opposedface so that the convex section can be fitted therein; when the convexsection and the concave section are fitted to each other and positioned,both the opposed faces are engaged with each other and the split sectionis prevented from being expanded again.

In the cage disclosed in Patent document 3, for the pair of the circularring sections (rim sections), on the opposite side of the deficitsection with respect to the center of the circular ring sections, thatis, at the outer circumferential portions dislocated by 180° in phasewith respect to the deficit section in the circumferential direction, asingle groove (slit) is provided so as to be concave in a nearly V-shapein a cross-sectional view in the axial direction, and on the outercircumferential face of the pillar section for connecting the portions,a single groove (slit) communicating with the groove in the circularring sections (rim sections) is also provided so as to be concave in anearly V-Shape in a cross-sectional view in the axial direction.

Since the grooves are provided in the circular ring sections (rimsections) and the pillar section, in the case that a force is exerted inthe circumferential direction to the cage so that both end faces (theopposed faces in the deficit section) of the circular ring sections (rimsections) are separated from each other, while the grooves in thecircular ring sections (rim sections) and the pillar section are used asfulcrums, the cage is elastically deformed so that the grooves arecollapsed. Hence, the split section can be expanded easily, that is, thecage can be increased in diameter easily. Furthermore, in the cagedisclosed in Patent document 4, the inner circumferential sections of apair of circular ring sections (rim sections) are made larger indiameter than the inner circumferential sections of pillar sectionsalong the entire circumference and made thinner than the pillar sectionsin the radial direction, whereby the split section thereof can beexpanded easily, that is, the cage can be increased in diameter easily.

RELATED ART REFERENCE Patent Reference

-   Patent document 1: JP-A-2008-261407-   Patent document 2: JP-A-S63-125221-   Patent document 3: German Patent Application Laid-Open Specification    No. 1815990-   Patent document 4: J JP-A-S57-86619

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

In the above-mentioned conventional single-split cage 2, the thicknessW1 (more specifically, the thickness W1 in the circumferentialdirection) of the one-side split region 10 a is set so as to be smallerthan the thickness W2 (more specifically, the thickness W2 in thecircumferential direction) of the other-side split region 10 b. In otherwords, the one-side split region 10 a is set so as to be thinner thanthe other-side split region 10 b, that is, the other-side split region10 b is set so as to be thicker than the one-side split region 10 a.

When attention is paid to the strength (rigidity) of the one-side splitregion 10 a and the other-side split region 10 b, the strength(rigidity) of the one-side split region 10 a being thin is made lowerthan the strength (rigidity) of the other-side split region 10 b beingthick. In this case, in the split section 10 of the single-split cage 2,the two split regions 10 a and 10 b being different from each other inthickness are formed, whereby a difference in strength (rigidity) occursbetween the split regions 10 a and 10 b.

In that case, depending on the degree of the difference in strength(rigidity), a state occurs in which it becomes difficult to uniformlymaintain (securely obtain) the strength (rigidity) of the entiresingle-split cage 2 in the circumferential direction; in the case that aplurality of rolling elements (rollers) are held in the single-splitcage 2 in this state, the one-side split region 10 a is degraded earlydue to an external force exerted to a portion being low in strength(rigidity), for example, and it becomes difficult to continuously holdthe rolling elements (rollers) stably for a long time; as a result,there is a danger that the single-split cage 2 is degraded early.

In addition, when attention is paid to the thicknesses W1 and W2 of theone-side split region 10 a and the other-side split region 10 b, anuneven chill (shrinkage cavity) is apt to occur in the thin split region10 a being thin and the thick split region 10 b being thick at the timewhen the single-split cage 2 made of a resin is injection molded. In thecase that such an uneven chill (shrinkage cavity) occurs in the twosplit regions 10 a and 10 b, in the split section 10, it becomesdifficult to maintain the dimensional accuracy between the one-sidesplit face Sa and the other-side split face Sb constant, whereby thesplit faces Sa and Sb cannot be disposed so as to be accurately opposedto each other.

Hence, depending on the degree of the uneven chill (shrinkage cavity),it becomes difficult that single-split cage 2 is maintained in a presetcontour shape (attitude); in the case that a plurality of rollingelements (rollers) are held in the single-split cage 2 in theabove-mentioned state, for example, it becomes difficult to continuouslyhold the plurality of rolling elements (rollers), incorporated betweenthe inner and outer rings, stably for a long time; as a result, there isa danger that the single-split cage 2 is degraded early.

Furthermore, when attention is paid to the disposition configuration ofthe one-side split face Sa and the other-side split face Sb at which thesplitting (separation) of the split regions 10 a and 10 b is performedin the split section 10, the split section 10 (the one-side and theother-side split faces Sa and Sb) is provided at a position relativelyaway from (dislocated from) the circumferential central position (morespecifically, the position in which the circumferential length betweenthe pockets 2 p on both sides in the circumferential direction isdivided in two) between the pockets 2 p on both sides thereof in thecircumferential direction.

In other words, the split section 10 (the one-side and the other-sidesplit faces Sa and Sb) is provided at a position away from (dislocatedfrom) the portion aligned with the interval pitch of the plurality ofpockets 2 p in the circumferential direction. From a different point ofview, the disposition position of the split section 10 (the one-side andthe other-side split faces Sa and Sb) and the circumferential centralposition between the pockets 2 p on both sides thereof in thecircumferential direction are relatively dislocated in phase in thecircumferential direction.

In this case, for example, when the single-split cage 2 is mounted at apredetermined position using an automatic assembly machine, it isnecessary to preset the mounting direction thereof. Hence, effort andtime are required in the assembly process, and the handling performanceand the assembling performance thereof are reduced, whereby thereduction of the cost for the assembly has a constant limit determinedby that amount. In the case that the cage is mounted in disregard of themounting direction, there is a danger that the single-split cage 2 isdamaged by a positioning pin that is used for the assembly process.

In addition, in the split section 10, it is conceivable that, forexample, the thickness W1 of the one-side split region 10 a is increased(expanded) as large as the thickness W2 of the other-side split region10 b so that the thickness of the one-side split region 10 a on whichthe one-side split face Sa is formed and the thickness of the other-sidesplit region 10 a on which the other-side split face Sa is formed becomeequal to each other (W1=W2). However, with this configuration, thenumber of the pockets 2 p is compelled to be reduced by the amount.Hence, the number of the rolling elements (rollers) is reduced; as aresult, the load capacity of the single-split cage 2 cannot bemaintained and improved.

Furthermore, in the single-split cage 2 according to Patent document 2,at the time of the minute movement (a movement for a countermeasure forfretting) of the cage during operation, the tapered end faces of theconcave and convex sections slide while generating component forces alsoin the axial direction, whereby there is a danger that the cage is wornor damaged.

Moreover, in the cage disclosed in Patent document 3 described above,when the split section is expanded, it is inevitable that the stress ofa force exerted to the cage is concentrated in the grooves of thecircular ring sections (rim sections) and the pillar section and in thevicinities thereof, whereby the cage is apt to be damaged starting fromthe grooves and there is a danger that the strength of the cage islowered. On the other hand, in the cage disclosed in Patent document 4described above, the pair of circular ring sections (rim sections) ismade uniformly thinner in the radial direction than the pillar sectionsaround the entire circumferences thereof; hence, it is assumed that whenthe split section is expanded, stress concentration in a specificportion can be avoided to some extent. On the other hand, since theinner circumferential sections of the pair of circular ring sections(rim sections) are made uniformly thin around the entire circumferencesthereof, in the case that an inner track is dented on the outercircumferential face of an inner member and the cage is used for engface guidance, there is a danger that the cage rides over the outercircumferential face of the inner member. In particular, in the casethat the configuration around a bearing is restricted, such a dangerousstate is apt to occur.

Still further, in the cage disclosed in Patent document 3 describedabove, in the case that the same number of rollers are held in the cagehaving the same diameter, the pillar sections become more slender as thediameter of the rollers becomes larger. On the other hand, as thediameter of the rollers to be held becomes larger, it is difficult toexpand the split section of the cage accordingly. In other words, thegroove (slit) provided in the pillar section is required to be expandedto easily expand the split section and to easily increase the cage indiameter; however, as the diameter of the rollers becomes larger, thepillar sections become more slender, whereby there is a restriction inthat the pillar section having a thickness (cross-sectional area)capable of allowing the groove (slit) to be expanded is obtainedsecurely. As a result, the number of the rollers to be held in the cageis inevitably required to be reduced, and there is a danger that theload capacity of the bearing is lowered.

The present invention is made to solve the above-mentioned problems andhas an object to provide a single-split cage capable of continuouslyholding a plurality of rolling elements stably for a long time byeliminating the difference in the strength (rigidity) between the splitregions, by maintaining the strength (rigidity) of the entire cageuniform in the circumferential direction and by maintaining thedimensional accuracy between the split regions constant at the time ofmolding and also capable of improving load capacity and achieving lowcost for assembly. Furthermore, the present invention has an object toprovide a radial roller bearing cage (a single-split cage as an example)capable of allowing its split section to be expanded easily andsufficiently and capable of effectively preventing from riding overtrack members (inner and outer members) while avoiding the deteriorationin strength and the reduction in the number of rollers to be held.

Means for Solving the Problem

For the purpose of attaining the above-mentioned objects, the presentinvention is attained by the following configurations.

(1) A single-split cage is equipped with a pair of circular ringsections having a circular ring shape and being disposed so as to beopposed to each other; a plurality of pillar sections continuouslyextending between the circular ring sections and arranged atpredetermined intervals in the circumferential direction; and aplurality of pockets formed in the portions enclosed by the pair ofcircular ring sections and the plurality of pillar sections and atpredetermined intervals in the circumferential direction, wherein in thesingle-split cage, a split section for splitting the cage at one portionin the circumferential direction thereof in a direction being crosswiseto the circumferential direction is provided; the split section isformed at regions extending between the pockets adjacent to each otherin the circumferential direction, and at the circumferential centerposition between these pockets, a one-side split face and the other-sidesplit face formed by splitting the regions are disposed so as to beopposed in the circumferential direction; engagement sections beingmutually engageable are respectively provided on the one-side split faceand the other-side split face, and these engagement sections aredisposed so as to be opposed to each other in the circumferentialdirection; and in a state in which the engagement sections of both theone-side split face and the other-side split face are mutually engaged,predetermined clearances are formed between the one-side split face andthe other-side split face and between the engagement sections.

(2) In the above-mentioned item (1), on the one-side split face, as theengagement sections, a plurality of one-side convex sections protrudingtoward the other-side split face and a one-side concave section formedby denting the area between these one-side convex sections are provided;on the other-side split face, as the engagement sections, a plurality ofother-side concave sections with which the plurality of one-side convexsections are engageable and an other-side convex section protrudingtoward the one-side split face between the other-side concave sectionsand engageable with the one-side concave section are provided; in astate in which the engagement sections of both the one-side split faceand the other-side split face are engaged with each other, predeterminedclearances are formed respectively between the one-side convex sectionand the other-side convex section and between the one-side concavesection and the other-side convex section; and in the clearances, theclearances between the mutual engagement sections in the circumferentialdirection are set so as to be smaller than the clearance between theone-side split face and the other-side split face in the circumferentialdirection.

(3) In the above-mentioned item (2), in a state in which both theengagement sections of both the one-side split face and the other-sidesplit face are engaged with each other, the clearance between theone-side split face and the other-side split face in the circumferentialdirection and the clearance between the engagement sections in thecircumferential direction are set so as to satisfy the relationship ofA>B=C, wherein the clearance formed between the one-side split face andthe other-side split face is A, the clearance formed between theone-side convex section and the other-side concave section is B, and theclearance formed between the one-side concave section and the other-sideconvex section is C.

(4) In the above-mentioned item (2) or (3), in a state in which both theengagement sections of the one-side split face and the other-side splitface are engaged with each other, the mutual clearances between theengagement sections in the direction perpendicular to thecircumferential direction are set so as to satisfy the relationship ofD>E, wherein the clearance formed between the one-side convex sectionand the other-side concave section is D, and the clearance formedbetween the one-side concave section and the other-side convex sectionis E.

(5) In any one of the above-mentioned items (2) to (4), on the one-sidesplit face, diameter-increase restricting concave sections are formed onthe axial outsides of the plurality of one-side convex sections; on theother-side split face, diameter-increase restricting convex sectionscapable of being engaged with the diameter-increase restricting concavesections are formed on the axial outsides of the plurality of theother-side concave section; and the axial side faces of thediameter-increase restricting concave section and the diameter-increaserestricting convex section, opposed to each other, are formed into atapered shape so as to make contact with each other when the splitsection is expanded in the circumferential direction.

(6) In the above-mentioned item (5), the clearance between thediameter-increase restricting concave section and the diameter-increaserestricting convex section, formed in a direction perpendicular to thecircumferential direction, is larger than the clearance between theone-side concave section and the other-side convex section, formed in adirection perpendicular to the circumferential direction.

(7) A single-split cage is equipped with a pair of circular ringsections having a circular ring shape and being disposed so as to beopposed to each other; a plurality of pillar sections continuouslyextending between the circular ring sections and arranged atpredetermined intervals in the circumferential direction; and aplurality of pockets formed in the portions enclosed by the pair ofcircular ring sections and the plurality of pillar sections and atpredetermined intervals in the circumferential direction, wherein in thesingle-split cage, a split section for splitting the cage at one portionin the circumferential direction thereof in a direction being crosswiseto the circumferential direction is provided; and in the pair ofcircular ring sections, the thickness of the start point sectionsthereof in the radial direction, dislocated from the split section by180° in phase in the circumferential direction, is formed so as to besmaller than the thickness in the vicinity of the split section in theradial direction.

(8) In the above-mentioned item (7), the pair of circular ring sectionshas thin sections and thick sections being different in thickness in theradial direction, the thin sections are positioned at the start pointsections, the thick sections are positioned in the vicinity of the splitsection; and the boundaries of the thin sections and the thick sectionsare positioned on the pockets.

(9) In the above-mentioned item (7), the pair of circular ring sectionshave thin sections and thick sections being different in thickness inthe radial direction, the thin sections are positioned at the startpoint sections, the thick sections are positioned in the vicinity of thesplit section; and the boundaries of the thin sections and the thicksections are positioned on the pillar sections.

(10) A single-split cage is equipped with a pair of rim sections and aplurality of pillar sections, wherein the pair of rim sections has adiscontinuous incomplete ring shape, respectively having deficitsections, each at one portion, and the deficit sections of the rimsections are disposed coaxially in the axial direction so as to beopposed to each other with a predetermined clearance providedtherebetween in a state in which the deficit sections have the samephase in the circumferential direction; the plurality of pillar sectionsare used to connect the pair of rim sections and to separate the regionbetween the rim sections in the circumferential direction of the rimsections, thereby forming pockets for allowing rollers serving asrolling elements to be inserted and held rotatably; the pair of rimsections has thin sections being thin in the radial direction, thediameter of the inner circumferential sections of which is made largerthan that of the inner circumferential section of the pillar section,and also has thick sections being thick in the radial direction, thediameter of which is made smaller than that of the thin sections; andthe thin sections are disposed at portions positioned on the oppositeside of the deficit sections with respect to the center of the innercircumferential sections of the pair of rim sections.

(11) In the above-mentioned item (10), the thin sections and the thicksections, plural in number, are disposed alternately on the innercircumferential sections of each of the rim sections, and the thinsections and the thick sections are disposed while respectively havingthe same phase in the circumferential direction.

(12) In the above-mentioned item (11), the boundaries of the thinsections and the thick sections adjacent to each other are positioned atportions in which the pair of rim sections is connected by the pillarsections.

(13) In the above-mentioned item (10), the thin sections and the thicksections are formed continuously without steps such that the innerdiameter is decreased gradually from the thinnest portions of the thinsections to the thickest portions of the thick sections.

(14) In any one of the above-mentioned items (10) to (13), thesingle-split cage is equipped with an engagement mechanism in which thediameter of the pair of rim sections can be increased by expanding thedeficit sections and the diameter of the pair of rim sections can bemaintained constant by preventing the expansion of the deficit sections.

(15) A single-split cage is equipped with a pair of rim sections and aplurality of pillar sections, wherein the pair of rim sections has adiscontinuous incomplete ring shape, respectively having deficitsections, each at one portion, and the deficit sections of the rimsections are disposed coaxially in the axial direction so as to beopposed to each other with a predetermined clearance providedtherebetween in a state in which the deficit sections have the samephase in the circumferential direction; the plurality of pillar sectionsare used to connect the pair of rim sections and to separate the regionbetween the rim sections in the circumferential direction of the rimsections, thereby forming pockets for allowing rollers serving asrolling elements to be inserted and held rotatably; the pair of rimsections has thin sections being thin in the radial direction, thediameter of the outer circumferential sections of which is made smallerthan that of the outer circumferential section of the pillar section,and also has thick sections being thick in the radial direction, thediameter of which is made larger than that of the thin sections; and thethin sections are disposed at portions positioned on the opposite sideof the deficit sections with respect to the center of the outercircumferential sections of the pair of rim sections.

(16) In the above-mentioned item (15), the inner circumferentialsections of the pair of rim sections are made larger in diameter thanthe inner circumferential sections of the pillar sections, whereby thethin sections are made thinner than the thick sections on both the outerdiameter sides and the inner diameter sides in the radial direction.

(17) In the above-mentioned item (16), the portions made thinner thanthe thick sections on the outer diameter sides in the radial directionand the portions made thinner than the thick sections on the innercircumferential sides in the radial direction are disposed in the samephase in the circumferential direction.

(18) In the above-mentioned item (16), the portions made thinner thanthe thick sections on the outer diameter sides in the radial directionand the portions made thinner than the thick sections on the innercircumferential sides in the radial direction are disposed in differentphases in the circumferential direction.

(19) In any one of the above-mentioned items (15) to (18), theboundaries of the thin sections and the thick sections are positioned atportions in which the pair of rim sections is connected by the pillarsections.

(20) A single-split cage is equipped with a pair of rim sections and aplurality of pillar sections, wherein the pair of rim sections has adiscontinuous incomplete ring shape, respectively having deficitsections, each at one portion, and the deficit sections of the rimsections are disposed coaxially in the axial direction so as to beopposed to each other with a predetermined clearance providedtherebetween in a state in which the deficit sections have the samephase in the circumferential direction; the plurality of pillar sectionsare used to connect the pair of rim sections and to separate the regionbetween the rim sections in the circumferential direction of the rimsections, thereby forming pockets for allowing rollers serving asrolling elements to be inserted and held rotatably; and the pair of rimsections are disposed so as to be opposed to each other in a state inwhich the centers of the inner circumferential sections thereof are madeeccentric with respect to the rotation axis of the cage to the oppositesides.

(21) In the above-mentioned item (20), the pair of rim sections has thinsections being thin in the radial direction, the diameter of the innercircumferential sections of which is made larger than that of the innercircumferential sections of the pillar sections, and also has thicksections being thick in the radial direction, the diameter of which ismade smaller than that of the thin sections; the thin sections aredisposed at portions positioned on the opposite side of the deficitsections with respect to the center of the inner circumferentialsections of the pair of rim sections; and the thin sections and thethick sections are formed continuously without steps such that the innerdiameter is decreased gradually from the thinnest portions of the thinsections to the thickest portions of the thick sections.

(22) In any one of the above-mentioned items (15) to (21), thesingle-split cage is equipped with an engagement mechanism in which thediameter of the pair of rim sections can be increased by expanding thedeficit sections and the diameter of the pair of rim sections can bemaintained constant by preventing the expansion of the deficit sections.

Advantage of the Invention

The present invention can realize a single-split cage capable ofcontinuously holding a plurality of rolling elements stably for a longtime by eliminating the difference in the strength (rigidity) betweenthe split regions, by maintaining the strength (rigidity) of the entirecage uniform in the circumferential direction and by maintaining thedimensional accuracy between the split regions constant at the time ofmolding and also capable of improving load capacity and achieving lowcost for assembly.

Furthermore, the present invention can realize a radial roller bearingcage (a single-split cage as an example) capable of allowing its splitsection to be expanded easily and sufficiently and capable ofeffectively preventing from riding over track members (inner and outermembers) while avoiding the deterioration in strength and the reductionin the number of rollers to be held.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic perspective view showing an entire configurationof a single-split cage according to a first embodiment of the presentinvention, FIG. 1B is a magnified plan view showing a peripheralconfiguration around the split section shown in FIG. 1A, and FIG. 1C isa magnified plan view showing positional relationships among theclearances in the split section shown in FIG. 1A;

FIG. 2 is a sectional view showing the single-split cage shown in FIG.1A, taken on line X-X of FIG. 1B;

FIGS. 3A and 3B are partially enlarged views showing a configuration ofa single-split cage according to a first modified example of the firstembodiment of the present invention, FIG. 3A is a sectional view takenon line Y-Y of FIG. 1B, and FIG. 3B is a sectional view showing anotherconfiguration example of the configuration shown in FIG. 3A;

FIG. 4 is a partially enlarged plan view showing an externalconfiguration of a single-split cage according to a second modifiedexample of the first embodiment of the present invention;

FIG. 5 is a partially enlarged plan view showing an externalconfiguration of a single-split cage according to a third modifiedexample of the first embodiment of the present invention;

FIG. 6A is a partially enlarged view showing an external configurationof a single-split cage according to a fourth modified example of thefirst embodiment of the present invention, FIG. 6B is a sectional viewtaken on line b-b of FIG. 6A, and FIG. 6C is a sectional view taken online c-c of FIG. 6B;

FIG. 7A is a partially enlarged view showing an external configurationof a single-split cage according to a fifth modified example of thefirst embodiment of the present invention, and FIG. 7B is an enlargedplan view showing positional relationships among the clearances in thesplit section shown in FIG. 7A;

FIG. 8 is a partially enlarged plan view showing an externalconfiguration of a single-split cage according to a sixth modifiedexample of the first embodiment of the present invention;

FIG. 9 is a partially enlarged plan view showing an externalconfiguration of a single-split cage according to a seventh modifiedexample of the first embodiment of the present invention;

FIG. 10 is a partially enlarged plan view showing an externalconfiguration of a single-split cage according to an eighth modifiedexample of the first embodiment of the present invention;

FIG. 11 is a partially enlarged plan view showing an externalconfiguration of a single-split cage according to a ninth modifiedexample of the first embodiment of the present invention;

FIG. 12 is a partially enlarged plan view showing an externalconfiguration of a single-split cage according to a tenth modifiedexample of the first embodiment of the present invention;

FIG. 13 is a perspective view showing an entire configuration of aradial roller bearing cage (single-split cage) according to a secondembodiment of the present invention;

FIG. 14 is a perspective view showing an entire configuration of aradial roller bearing cage (single-split cage) according to a thirdembodiment of the present invention;

FIG. 15 is a perspective view showing an entire configuration of aradial roller bearing cage (single-split cage) according to a fourthembodiment of the present invention;

FIG. 16 is a perspective view showing an entire configuration of aradial roller bearing cage (single-split cage) according to a fifthembodiment of the present invention;

FIGS. 17A and 17B are perspective views showing an entire configurationof a radial roller bearing cage (single-split cage) according to a sixthembodiment of the present invention;

FIG. 18 is a perspective view showing an entire configuration of aradial roller bearing cage (single-split cage) according to a seventhembodiment of the present invention;

FIG. 19 is a perspective view showing an entire configuration of aradial roller bearing cage (single-split cage) according to an eighthembodiment of the present invention;

FIG. 20 is a perspective view showing an entire configuration of aradial roller bearing cage (single-split cage) according to a ninthembodiment of the present invention;

FIG. 21 is a perspective view showing an entire configuration of aradial roller bearing cage (single-split cage) according to a tenthembodiment of the present invention;

FIG. 22 is a perspective view showing an entire configuration of aradial roller bearing cage (single-split cage) according to an 11thembodiment of the present invention;

FIG. 23 is a perspective view showing an entire configuration of aradial roller bearing cage (single-split cage) according to a 12thembodiment of the present invention;

FIG. 24 is a perspective view showing an entire configuration of aradial roller bearing cage (single-split cage) according to a 13thembodiment of the present invention; and

FIG. 25 is a schematic perspective view showing an entire configurationof the conventional single-split cage.

MODES FOR CARRYING OUT THE INVENTION

A single-split cage according to a first embodiment of the presentinvention will be described below referring to the accompanyingdrawings.

Since this embodiment is an improvement of the single-split cage 2 shownin FIG. 15, only the improved portions thereof will be described below.In this case, with respect to the same components as those of theabove-mentioned single-split cage, the same codes as the reference codesassigned to the components are assigned in the drawings, and theirdescriptions are omitted.

As shown in FIGS. 1A to 2, in the single-split cage 2 according to thisembodiment, a split section 10 for splitting the cage at one portion inthe circumferential direction thereof is provided along a directionbeing crosswise to (perpendicular to) the circumferential direction. Thesplit section 10 is formed at regions (that is, split regions 10 a and10 b) extending between pockets 2 p adjacent to each other in thecircumferential direction, and at the circumferential central positionbetween these pockets 2 p, a one-side split face Sa and the other-sidesplit face Sb formed by splitting to two split regions, the splitregions 10 a and 10 b, are disposed so as to be opposed to each other inthe circumferential direction.

The circumferential central position between the pockets 2 p in whichthe split section 10 (the one-side and the other-side split faces Sa andSb) is disposed will be described herein.

It is preferable that the circumferential central position should be setat a position in which the circumferential length between the pockets 2p on both sides of the split section 10 (the one-side and the other-sidesplit faces Sa and Sb) in the circumferential direction is split intotwo halves. In other words, it is preferable that the circumferentialcentral position of the split section 10 should be set so that whilerolling elements (rollers) 16 are held in the respective pockets 2 pbeing adjacent to each other in the circumferential direction at thesplit section 10 (FIG. 1B and FIG. 2), the line segments extending fromthe rotation axis Z of the cage 2 to the rotation centers 16 r of therolling elements (rollers) 16 have angles θα being equal to each otherin the circumferential direction.

Furthermore, in the single-split cage 2 in which the rolling elements(rollers) 16 are held in the respective pockets 2 p (FIG. 1B and FIG.2), the line segments extending from the rotation axis Z of the cage 2to the rotation centers 16 r of the rolling elements (rollers) 16 haveangles θ being equal to each other in the circumferential direction. Inthis case, it may be possible that θα=θ or θα≠θ.

In both cases, in the regions (the split regions 10 a and 10 b)extending between the pockets 2 p (the rolling elements (rollers) 16) onboth sides of the split section 10 in the circumferential direction, thethickness W1 (more specifically, the thickness W1 in the circumferentialdirection) of the one-side split region 10 a on which the one-side splitface Sa is formed and the thickness W2 (more specifically, the thicknessW2 in the circumferential direction) of the other-side split region 10 bon which the one-side split face Sb is formed are set so as to have thesame thickness (W1=W2) (FIG. 1B).

Moreover, in the single-split cage 2 in which the thicknesses of thesplit regions 10 a and 10 b are set so as to be equal to each other(W1=W2), engagement sections being mutually engageable are respectivelyprovided on the split section 10 (the one-side split face Sa and theother-side split face Sb), and these engagement sections are disposed soas to be opposed to each other in the circumferential direction. Inaddition, in a state in which the engagement sections of both theone-side split face Sa and the other-side split face Sb are engaged witheach other, predetermined clearances are formed between the one-sidesplit face Sa and the other-side split face Sb and between theengagement sections.

More specifically, on the one-side split face Sa, as the engagementsections, a plurality (for example, two in the figure) of one-sideconvex sections 18 protruding toward the other-side split face Sb and aone-side concave section 20 formed by denting the area between theseone-side convex sections 18 are provided. On the other hand, on theother-side split face Sb, as the engagement sections, a plurality (forexample, two in the figure) of other-side concave sections 22 into whichthe plurality of one-side convex sections 18 are partly inserted so asto be engageable and an other-side convex section 24 protruding towardthe one-side split face Sa between the other-side concave sections 22and partly inserted into the one-side concave section 20 so as to beengageable are provided.

In other words, in this embodiment, the axial inner face 18 s of theone-side convex section 18 constitutes the axial side face 20 s of theone-side concave section 20, and the axial inner face 22 s of theother-side concave section constitutes the axial side face 24 s of theother-side convex section 24; these are formed so as to be in parallelwith each other in the circumferential direction.

Although the shapes of the convex sections 18 and 24 and the concavesections 20 and 22 are shown as being rectangular in the drawings, theyare not limited to this shape. The point is that, provided that theshapes are formed, for example, so that the mutual dislocation (morespecifically, the dislocation in a direction along the rotation axis Zof the single-split cage 2 revolving along the space between the innerand outer rings during bearing rotation) between the split faces Sa andSb when the single-split cage 2 is mounted between the inner and outerrings can be prevented, the shapes can be set as desired, such astriangular or circular. Furthermore, the sizes and the numbers of theconvex sections 18 and 24 and the concave sections 20 and 22 are set,for example, depending on the sizes of the split regions 10 a and 10 band the intended use and the use environment of the single-split cage 2,thereby not limited particularly herein.

In a state in which the engagement sections of both the one-side splitface Sa and the other-side split face Sb are engaged with each other,predetermined clearances are formed respectively between the one-sideconvex section 18 and the other-side convex section 22 and between theone-side concave section 20 and the other-side convex section 24. Inthis case, in the clearances, the clearances between the engagementsections in the circumferential direction are set so as to be smallerthan the clearance between the one-side split face Sa and the other-sidesplit face Sb in the circumferential direction.

More specifically, in the state in which both the engagement sectionsare engaged with each other, it is preferable that the clearance betweenthe one-side split face Sa and the other-side split face Sb in thecircumferential direction and the clearances between the engagementsections in the circumferential direction are set so as to satisfy therelationship of:

A>B=C

wherein the clearance formed between the one-side split face Sa and theother-side split face Sb is A,

the clearance formed between the one-side convex section 18 and theother-side concave section 22 is B, and

the clearance formed between the one-side concave section 20 and theother-side convex section 24 is C (FIG. 1C).

Nonetheless, the clearance B and the clearance C are not necessarily setso as to be equal (B=C); for example, the clearance B can be made largerthan the clearance C (B>0), or conversely, the clearance B can be madesmaller than the clearance C (B<C) depending on the sizes of the splitregions 10 a and 10 b and the intended use and the use environment ofthe single-split cage 2. However, in both cases, it is preferable thatthe clearances B and C are set so as to be smaller than the clearance A.

Furthermore, it is preferable that the mutual clearances between theengagement sections should be considered not only in the above-mentionedcircumferential direction but also in a direction perpendicular to thecircumferential direction.

In other words, in the state in which both the engagement sections ofthe one-side split face Sa and the other-side split face Sb are engagedwith each other, it is preferable that the mutual clearances between theengagement sections in the direction perpendicular to thecircumferential direction are set so as to satisfy the relationship of:

D>E

wherein the clearance formed between the one-side convex section 18 andthe other-side concave section 22 is D, and

the clearance formed between the one-side concave section 20 and theother-side convex section 24 is E (FIG. 1C).

When the positional relationship between the clearance D and theclearance E is described, the clearance D can be defined, for example,as a clearance formed between the one-side convex section 18 and theother-side concave section 22 on the outside (that is, close to circularring sections 4 and 6) of each of the two one-side convex sections 18.On the other hand, the clearance E can be defined, for example, as aclearance formed between the one-side concave section 20 and theother-side convex section 24 on the outside (that is, close to thecircular ring sections 4 and 6) of the one-side concave section 20.

With this embodiment, since the split section 10 is set at thecircumferential central position between the pockets 2 p as describedabove, the thickness W1 of the one-side split region 10 a on which theone-side split face Sa is formed and the thickness W2 of the other-sidesplit region 10 b on which the other-side split face Sb is formed can beset so as to be equal to each other (W1=W2).

In this case, when attention is paid to the strength (rigidity) of theone-side split region 10 a and the other-side split region 10 b, sincethe thicknesses of the split regions 10 a and 10 b are made equal(W1=W2), the strength (rigidity) of the one-side split region 10 ahaving the thickness W1 and the strength (rigidity) of the other-sidesplit region 10 b having the thickness W2 can be made equal (uniform).In other words, the difference in strength (rigidity) between thesesplit regions 10 a and 10 b can be eliminated.

Hence, the strength (rigidity) of the entire single-split cage 2 can bemaintained (securely obtained) uniformly in the circumferentialdirection. For this reason, for example, in a state in which a pluralityof rolling elements (rollers) are held in the single-split cage 2, evenin the case that an external force is exerted during bearing rotation,the external force can be exerted uniformly as a load on the entire cage2, whereby the durability (anti-fretting performance) of thesingle-split cage 2 can be maintained and improved; as a result, therolling elements (rollers) can be continuously held stably for a longtime.

Furthermore, when attention is paid to the thicknesses W1 and W2 of theone-side split region 10 a and the other-side split region 10 b, anuneven chill (shrinkage cavity) does not occur in both the split regions10 a and 10 b at the time when the single-split cage 2 made of a resinis injection molded. In this case, in the split section 10 having beenmolded, the dimensional accuracy between the one-side split face Sa andthe other-side split face Sb can be maintained constant; as a result,the split faces Sa and Sb can be disposed so as to be accurately opposedto each other.

With this configuration, the single-split cage 2 can be maintained in apreset contour shape (attitude). Hence, for example, a plurality ofrolling elements (rollers) can be held stably in the single-split cage2, whereby the bearing can be rotated stably for a long time.

Furthermore, when attention is paid to the disposition configuration ofthe one-side split face Sa and the other-side split face Sb at which thesplitting (separation) of the split regions 10 a and 10 b is performedin the split section 10, the split section 10 (the one-side and theother-side split faces Sa and Sb) can be provided at the circumferentialcentral position (more specifically, the position in which thecircumferential length between the pockets 2 p on both sides in thecircumferential direction is divided in two) between the pockets 2 p onboth sides thereof in the circumferential direction.

In this case, for example, when the single-split cage is mounted at apredetermined position by an automatic assembly machine, a process ofpresetting its mounting direction becomes unnecessary. Hence, theassembly process can be made efficient, whereby the handling andassembly performance thereof can be improved significantly. As a result,the cost for the assembly can be reduced drastically.

Furthermore, with this embodiment, the mutual dislocation between thesplit faces Sa and Sb at the time when the single-split cage 2 ismounted between the inner and outer rings can be prevented sufficientlyonly by the engagement sections of the split section 10. In this case,the clearance A formed between the one-side split face Sa and theother-side split face Sb can be set as desired. Hence, for example, theclearance A can be set to a size capable of allowing a positioning pin26 (FIG. 1B) that is used for the assembly process to be inserted; as aresult, a problem in which the single-split cage 2 itself is damaged bythe positioning pin 26 can be prevented from occurring.

Moreover, with this embodiment, the split section 10 (the one and theother split faces Sa and Sb) can be provided at the circumferentialcentral position (the position in which the circumferential lengthbetween the pockets 2 p on both sides in the circumferential directionis divided in two) between the pockets 2 p on both sides thereof in thecircumferential direction. In this case, the split regions 10 a and 10 bbetween the pockets 2 p are not required to be increased, whereby theabove-mentioned engagement sections can be formed without reducing thenumber of the pockets 2 p. Hence, the number of the rolling elements(rollers) to be incorporated can be maintained unchanged or can beimproved; as a result, the load capacity of the single-split cage 2 canbe maintained and improved.

However, the present invention is not limited to the above-mentionedembodiment, and technological ideas relating to the following modifiedexamples are also included in the technological scope of the presentinvention.

As a first modified example, at the engagement sections of the splitsection 10, steps may be formed in the radial direction (a directionperpendicular to the rotation axis Z of the single-split cage 2revolving along the space between the inner and outer rings duringbearing rotation). As one example, a configuration is shown in whichsteps are provided in the radial direction on the one-side concavesection 20 and the other-side convex section 24 in the engagementsections.

Herein, as the steps in the radial direction, on the one-side concavesection 20, a protruding section 20 a protruding from a part thereof(the inside diameter side in the figure as an example) toward theother-side convex section 24 is formed, and on the other-side convexsection 24, a hollow section 24 a into which a part of the protrudingsection 20 a is inserted so as to be engageable is formed by denting apart (the inside diameter side in the figure as an example) of theother-side convex section 24.

The shapes and sizes of the protruding section 20 a and the hollowsection 24 a are set, for example, depending on the shapes and sizes ofthe one-side concave section 20 and the other-side convex section 24 andthus not be limited particularly.

For example, as shown in FIG. 3B, it may be possible that the protrudingsection 20 a is formed at the center of the one-side concave section 20in the radial direction and that the hollow section 24 a is formed atthe center of the other-side convex section 24 in the radial direction.

In the first modified example, the steps (FIGS. 3A and 3B) in the radialdirection are formed at the engagement sections of the split section 10as described above; hence, the protruding section 20 a is engaged withthe hollow section 24 a in the radial direction while the engagementsections of both the one-side split face Sa and the other-side splitface Sb are engaged with each other; consequently, the single-split cage2 can be prevented from expanding in the radial direction and fromincreasing in diameter (expanding) via the split section 10.

As a second modified example, as shown in FIG. 4, the end faces 18 t ofthe one-side convex sections 18 on the outsides (that is, close to thecircular ring sections 4 and 6) of the respective one-side convexsections 18 may be tapered. With this configuration, the strength(rigidity) of the root portions (more specifically, the portionscontinuously extending from the end faces 18 t to the one-side splitface Sa) of the respective one-side convex sections 18 can be raised. Asa result, the durability of the engagement sections of the split section10 can be improved. Furthermore, in correspondence with the formation ofthe taper on the end faces 18 t of the one-side convex sections 18, itis preferable that tapered end faces 22 t should also be formed so as tobe opposed to the above-mentioned end faces 18 t on the other-sideconcave sections 22 into which parts of the one-side convex sections 18are inserted so as to be engaged.

As a third modified example, as shown in FIG. 5, in the split section10, chamfers 4 r and 6 r are respectively provided on the edge sections(corner sections) extending from the one-side split face Sa and theother-side split face Sb to the circular ring sections 4 and 6. Withthis configuration, the positioning pin 26 (FIG. 1B) to be used for theabove-mentioned assembly process can be easily inserted into theclearance A, and the efficiency of the assembly process can be improvedfurther. The shape of the chamfers 4 r and 6 r is circular in the figureas an example; however, the shape is not limited to this, but may beelliptical, for example.

As a fourth modified example, as shown in FIGS. 6A to 6C, lubricityimproving means may be provided for the single-split cage 2. In thiscase, as an example of the lubricity improving means, on the outercircumferential sides of a plurality of pillar sections 8, lubricantstorage grooves 28 extending along the pillar sections 8 are formed. Inaddition, tapered faces 4 t and 6 t continuously extending in thecircumferential direction are formed respectively on the outercircumferential sides of the circular ring sections 4 and 6, and stepsections 4 g and 6 g being dented from the other portions are formedrespectively on the inner circumferential sides of the circular ringsections 4 and 6.

The lubricant storage groove 28 may be formed for all of the pluralityof pillar sections 8 or may be formed for only the arbitrarily selectedpillar sections 8; however, it is preferable that the lubricant storagegrooves 28 should be formed at equal intervals in the circumferentialdirection so that the lubricant (for example, grease or oil)accommodated in the lubricant storage grooves 28 is distributeduniformly to the entire single-split cage 2.

The groove width, groove depth and groove length of the lubricantstorage groove 28 are set, for example, depending on the size, shape,etc. of the pillar section 8, thereby not limited particularly herein.Furthermore, the cross-sectional shape of the lubricant storage groove28 is trapezoidal close to triangular as an example in the figure;however, the shape is not limited to this, and various shapes, such ascircular or rectangular shapes, may be applied. The point is that theshape should only be a shape capable of accommodating lubricant (forexample, grease or oil).

Furthermore, the inclination angle of the tapered faces 4 t and 6 t andthe hollow amount and hollow shape of the step sections 4 g and 6 g areset, for example, depending on the use environment and the intended useof the single-split cage 2 or the size, shape, etc of the circular ringsections 4 and 6, thereby not limited particularly herein. The point isthat the inclination angle of the tapered faces 4 t and 6 t and thehollow amount and hollow shape of the step sections 4 g and 6 g shouldonly be set so that lubricant (for example, grease or oil) can beefficiently circulated as the single-split cage 2 revolves duringbearing rotation.

In the fourth modified example, the lubricity improving means (thelubricant storage grooves 28, the tapered faces 4 t and 6 t and the stepsections 4 g and 6 g) are provided for the single-split cage 2 asdescribed above; hence, lubricant (for example, grease or oil) can bedistributed uniformly to the entire single-split cage 2 in addition tothe effect of the above-mentioned first embodiment, and lubricant (forexample, grease or oil) can be circulated efficiently as thesingle-split cage 2 revolves during bearing rotation.

In the fifth modified example shown in FIGS. 7A and 7B, on the one-sidesplit region 10 a, a plurality of diameter-increase restricting concavesections 30 are formed on both the axial outsides of the plurality ofone-side convex sections 18 provided as the engagement sections, and onthe other-side split region 10 b, diameter-increase restricting convexsections 32 capable of being engaged with the diameter-increaserestricting concave sections 30 are formed on both the axial outsides ofthe plurality of the other-side concave section 22 provided as theengagement sections.

The axial inner face 30 t of the diameter-increase restricting concavesection 30 constitutes the axial outside face 18 t of the one-sideconvex section 18, and the axial inner face 32 t of thediameter-increase restricting convex section 32 constitutes the axialouter face 22 t of the other-side concave section 22.

In addition, the axial inner face 30 t of the diameter-increaserestricting concave section 30 and the axial inner face 32 t of thediameter-increase restricting convex sections 32 are respectively formedinto tapered shapes being in parallel with each other, and make contactwith each other, thereby being capable of suppressing the split section10 from being opened excessively when a force is exerted in thecircumferential direction so that the split section 10 is expanded. Inother words, the tip end face of the diameter-increase restrictingconvex section 32 and the tip end face of the one-side convex section 18constituting the axial inner face 30 t of the diameter-increaserestricting concave section 30 are overlapped with each other as viewedfrom the circumferential direction.

The clearance between the axial inner face 30 t of the diameter-increaserestricting concave section 30 and the axial inner face 32 t of thediameter-increase restricting convex sections 32 is defined as theclearance D formed between the one-side convex section 18 and theother-side concave section 22 and is set so as to satisfy therelationship of D>E as in the above-mentioned embodiment. Furthermore,the clearance I between the axial outer face 30 o of thediameter-increase restricting concave section 30 and the axial outerface 32 o of the diameter-increase restricting convex sections 32 isalso set so as to satisfy the relationship of I>E.

Moreover, when it is assumed that the clearance formed between thediameter-increase restricting concave section 30 and thediameter-increase restricting convex sections 32 in the circumferentialdirection is J, it is preferable that the clearance should only be setso as to satisfy the relationship of A>J and should preferably be set soas to satisfy the relationship of A>B=C=J.

Hence, in the fifth modified example, the split section 10 can beprevented from being opened excessively when the cage 2 is mounted in atransmission, etc., and the one-side concave section 20 and theother-side convex section 24 can be used for guidance during operation,whereby abrasion and damage of the cage 2 can be suppressed.

In a sixth modified example shown in FIG. 8, unlike the single-splitcage 2 according to the fifth modified example, the single-split cage 2is configured so that the one-side split region 10 a and the other-sidesplit region 10 b are restricted from being dislocated in the radialdirection; among the plurality of diameter-increase restricting convexsections 32, the inner diameter side of the one diameter-increaserestricting convex section 32 is partially cut off to form a step in theradial direction, and the outer diameter side of the otherdiameter-increase restricting convex section 32 is partially cut off toform a step in the radial direction. Furthermore, the protruding section18 a formed by extending the inner diameter side of the adjacentone-side convex section 18 into the diameter-increase restrictingconcave section 30 so as to protrude toward the hollow section 32 a isengaged with the hollow section 32 a formed in the diameter-increaserestricting convex sections 32, the inner diameter side of which is cutoff; and the protruding section 18 a formed by extending the outerdiameter side of the adjacent one-side convex section 18 into thediameter-increase restricting concave section 30 so as to protrudetoward the hollow section 32 a is engaged with the hollow section 32 aformed in the diameter-increase restricting convex sections 32, theouter diameter side of which is cut off.

In the sixth modified example, the step in the radial direction isformed by partially cutting off the inner diameter side or the outerdiameter side of the diameter-increase restricting convex sections 32;however, as in a seventh modified example shown in FIG. 9, a step in theradial direction may be formed by cutting off the entire inner diameterside or the entire outer diameter side of the diameter-increaserestricting convex sections 32 in the axial direction. In this case, theprotruding section 18 a formed on the one-side convex section 18 can beformed so as to be larger than that in the sixth modified example,whereby the opposed faces of the hollow section 32 a and the protrudingsection 18 a for restricting the one-side split region 10 a and theother-side split region 10 b are dislocated in the radial direction canbe made wider securely.

In an eighth modified example shown in FIG. 10, as a partial improvementof the single-split cage 2 according to the above-mentioned firstembodiment (more specifically, the second modified example shown in FIG.4), a hollow section 200 may be formed by partially denting the axialcentral portion of the other-side convex section 24 (in other words, bypartially cutting off the central portion).

The size of the hollow section 200 is set depending on the size of theother-side convex sections 24; hence, the size is not limited partiallyherein. In addition, the shape of the hollow section 200 can be formedinto a desired shape, such as trapezoidal, rectangular, triangular orcircular. In FIG. 10, as an example, the hollow section 200 having atrapezoidal shape in a plan view is shown; with this configuration,tapered faces 200 s having a shape being narrowed toward the hollowingdirection are formed on both sides of the trapezoidal hollow section200, whereby the strength (rigidity) of the respective other-side convexsections 24 remaining on both sides of the hollow section 200 can beimproved. However, the tapered faces 200 s are not necessarily requiredto be formed.

With this kind of configuration, it is preferable that thecircumferential clearances F1 and F2 between the other-side convexsections 24 remaining on both sides of the hollow section 200 and theone-side concave section 20 and the clearances G1 and G2 between theone-side convex sections 18 and the other-side concave sections 22should be set so as to satisfy the relationships of F1=F2 and G1=G2. Atthis time, the magnitude relationship between F1 (=F2) and G1 (=G2) maybe set so as to satisfy the relationship of F1 (=F2)>G1 (=G2) or may beset so as to satisfy the relationship of F1 (=F2)<G1 (=G2).

In this modified example, the hollow section 200 is formed in theother-side convex section 24 as described above; hence, the differencein volume (difference in thickness) from the other pillar sections 8 canbe reduced by that amount thereof, whereby the influence of “shrinkage”or the like during cage molding can be suppressed and the moldability(molding accuracy) can be improved. The other effects are similar tothose of the above-mentioned first embodiment and their descriptions areomitted.

In addition, in the embodiment and the respective modified examplesdescribed above, the single-split cage 2 of a single-row type has beenassumed to be used and described; however, the technological idea of thepresent invention can also be applied to a single-split cage of adouble-row type. As a ninth modified example, FIG. 11 shows asingle-split cage 2 of a double-row type in which the configuration ofthe single-split cage 2 shown in FIG. 10 is disposed on both sides inthe axial direction while being centered at the central pillar portion202 extending in the circumferential direction from the one-side splitregion 10 a to the other-side split region 10 b.

In this case, it is preferable that a protruding section 204 formed bypartially protruding the axial central portion of the one-side concavesection 20 should be formed toward the axial central portion of thehollow section 200. In this configuration, the size of the protrudingsection 204 is set depending on the width of the hollow section 200,thereby not limited particularly herein. Furthermore, the shape of theprotruding section 204 can be formed into a desired shape, such astrapezoidal, rectangular, triangular or circular. In FIG. 11 as anexample, the protruding section 204 having a trapezoidal shape in a planview is shown; with this configuration, tapered faces 204 s having ashape being narrowed toward the direction of the protrusion are formedon both sides of the trapezoidal protruding section 204, whereby thestrength (rigidity) of the single-split cage 2 of the double-row typecan be improved. However, the tapered faces 204 s are not necessarilyrequired to be formed.

Moreover, it is preferable that the configuration position of theprotruding section 204 should be set so as to be aligned in thecircumferential direction along the central pillar portion 202. Hence,the strength (rigidity) of the single-split cage 2 of the double-rowtype can be improved further, and the balance of the single-split cage 2can be maintained and improved.

With this kind of configuration, it is preferable that thecircumferential clearance H between the protruding section 204 and thehollow section 200 should be set so as to be aligned with (that is,coincident with) the circumferential clearances between the other-sideconvex sections 24 remaining on both sides of the hollow section 200 andthe one-side concave section 20 or the circumferential clearances G1 andG2 between the one-side convex sections 18 and the other-side concavesections 22, whichever smaller. It is preferable that thecircumferential clearances F1 and F2 and the circumferential clearancesG1 and G2 should be set so as to satisfy the relationships of F1=F2 andG1=G2. At this time, the magnitude relationship between F1 (=F2) and G1(=G2) may be set so as to satisfy the relationship of F1 (=F2)>G1 (=G2)or may be set so as to satisfy the relationship of F1 (=F2)<G1 (=G2).

With this modified example, the protruding section 204 is formed asdescribed above; hence, the thicknesses in the vicinities of the cornersections 2 r on the side of the central pillar portion 202 and close tothe protruding section 204 in the pair of pockets 2 p adjacent to theprotruding section 204 can be securely obtained sufficiently, wherebythe strength (rigidity) of the single-split cage 2 of the double-rowtype can be maintained constant. The other effects are similar to thoseof the single-split cage 2 shown in FIG. 10 and their descriptions areomitted.

In FIG. 11, the axial central portion of the one-side concave section 20is partially protruded to form the protruding section 204; however,instead of this, the hollow section 200 may be partially protruded toform a protruding section protruded in the opposite direction, orprotruding sections may be protruded from both the one-side concavesection 20 and the hollow section 200.

As a tenth modified example, FIG. 12 shows a single-split cage 2 of adouble-row type configured so that the protruding sections 204 areprotruded from both the one-side concave section 20 and the hollowsection 200. In this case, the circumferential clearance H between theprotruding sections 204 should only be set so as to be aligned with(that is, coincident with) the circumferential clearances F1 and F2 orthe circumferential clearances G1 and G2, whichever smaller.

With this kind of configuration, the protruding sections 204 are formedso as to protrude from both the one-side concave section 20 and thehollow section 200; hence, the thicknesses in the vicinities of thecorner sections 2 r on the side of the central pillar portion 202 andclose to the respective protruding sections 204 in the respectivepockets 2 p adjacent to the respective protruding sections 204 can besecurely obtained sufficiently, whereby the strength (rigidity) of thesingle-split cage 2 of the double-row type can be maintained constant.The other effects are similar to those of the single-split cage 2 shownin FIG. 10 and their descriptions are omitted.

In the embodiment and the respective modified examples described above,it is assumed that the single-split cage 2 is entirely molded (forexample, injection molded) using a resin (for example, thermoplasticresin); however, even if the single-split cage 2 is formed using anelastic material other than a resin, configurations similar to those ofthe embodiment and the respective modified examples described above canbe applied and similar effects can be accomplished.

Next, radial roller bearing cages according to other embodiments of thepresent invention will be described referring to the accompanyingdrawings. An object of each of the other embodiments described later isto provide a radial roller bearing cage (a single-split resin cage as anexample) capable of allowing its split section to be expanded easily andsufficiently and capable of effectively preventing from riding overinner members while avoiding the deterioration in strength and thereduction in the number of rollers to be held, and technological ideasfor accomplishing this object are described.

It is possible to assume that bearings or the like for journalingrotating systems in power mechanisms (an automobile transmission as anexample) provided for automobiles, railroad vehicles, etc. are used asbearings in which the radial roller bearing cage according to thepresent invention is incorporated; however, the bearings are not limitedto these bearings.

Such a bearing is equipped with an outer member (for example, an outerring or a housing being maintained in a non-rotating state at all times,or a gear, a roller, etc. being rotatable during use) having acylindrical outer track on the inner circumferential face thereof; and aplurality of radial rollers (a plurality of needles as an example)incorporated so as to be able to roll between the outer circumferentialface (inner track) of the inner member (for example, an inner ring, ashaft, etc. being rotatable during use) disposed on the inner diameterside of the outer member and the outer track. The size of the bearing,the presence or absence of the inner ring, the size (diameter andlength) and the number of the rollers, etc. can be set as desireddepending on the use conditions, the intended use of the bearing, etc.,thereby not limited particularly herein.

In addition, when these rollers roll between the tracks (the outer trackand the inner track), the rollers are held by the bearing cage so as tobe rotatable inside the pockets thereof to prevent the increase inrotational resistance, seizure, etc. caused by the friction due tomutual contact between the rollers. Bearing lubrication (oil lubricationor grease lubrication) may be performed to further effectively preventthe increase in rotational resistance, seizure, etc.

FIG. 13 shows the configuration of a radial roller bearing cage(hereafter referred to as a single-split cage) 102 according to a secondembodiment of the present invention. In this embodiment, it is assumedthat the single-split cage 102 is made of a predetermined elasticmaterial (a resin as an example) and that the whole of the cage (rimsections 104 a and 104 b and pillar sections 106 described later) isintegrally molded by injecting the elastic material into a metal mold(injection molding); however, this does not eliminate the possibility ofperforming molding using other known methods. Furthermore, it may bepossible that a molded body obtained after injection molding issubjected to cutting, grinding, etc. separately to form the single-splitcage 102 as a completed product.

The single-split cage 102 is configured so as to be equipped with a pairof circular ring sections 104 a and 104 b (hereafter referred to as rimsections) and a plurality of pillar sections 106, and is split at oneportion in the circumferential direction thereof along a direction beingcrosswise to (perpendicular to) the circumferential direction. In thesplit region, the pair of rim sections 104 a and 104 b has adiscontinuous incomplete ring shape (nearly C-shaped), respectivelyhaving deficit sections 108 a and 108 b, each at one portion, and thedeficit sections 108 a and 108 b of the respective rim sections 104 aand 104 b are disposed coaxially in the axial direction so as to beopposed to each other with a predetermined clearance providedtherebetween in a state in which the deficit sections 108 a and 108 bhave the same phase in the circumferential direction (in a state inwhich the positions of the deficit sections 108 a and 108 b in thecircumferential direction are coincident with each other). In otherwords, the single-split cage 102 has, as an appearance profile, a nearlycylindrical shape (the so-called single-split cage structure) having asingle split section 120 (hereafter referred to as a crack section) inthe circumferential direction. The diameter of the rim section 104 a andthe rim section 104 b and the distance between the opposed sections inthe axial direction should only be set as desired depending on the sizeof the bearing, etc.

The plurality of pillar sections 106 are used to connect the pair of rimsections 104 a and 104 b in the axial direction and to separate theregion between the rim sections 104 a and 104 b in the circumferentialdirection, thereby forming pockets 110 for allowing rollers (needles)serving as rolling elements, not shown, to be inserted and heldrotatably. In other words, a single pocket 110 is formed in the spaceenclosed by the two pillar sections 106 being adjacent to each other inthe circumferential direction and the pair of rim sections 104 a and 104b. Hence, the single-split cage 102 has a structure in which the pillarsections 106 and the pockets 110 are disposed alternately in thecircumferential direction. However, in the region between the rimsections 104 a and 104 b separated by the two pillar sections 106(hereafter referred to as deficit-section-adjacent pillar sections 162and 164) disposed close to both the circumferential sides of the deficitsections 108 a and 108 b of the rim sections 104 a and 104 b, the cracksection (split section) 120 is present, and no pocket 110 is formed.Hence, the single-split cage 102 has a structure in which a roller islacking only in this region (that is, the crack section 120); in otherwords, the cage has a structure in which in the regions other than thisregion, the rollers are inserted into the pockets, one by one, and therollers are disposed at equal intervals (at equal pitches) in thecircumferential direction.

The size of the pocket 110 formed by the pillar sections 106 should onlybe set depending on the diameter and length of the roller so that theroller can be held so as to be rotatable in the pocket 110, and thenumber of the pockets 110 (the number of the pillar sections 106 from adifferent point of view) should only be set as desired depending on thecapacity (the number of the rollers to be held) of the cage 102. Inaddition, the shape (the surface shape of the circumferentially opposedfaces of the adjacent pillars 106 from a different point of view) of thepocket face (the face making contact with the circumferential face ofthe roller) should only be formed into a concave curved shape (forexample, a concave curved shape having a curvature slightly smaller thanthat of the circumferential face of the roller). In the peripheralsection of the pocket 110, it is possible to provide protruding sections(for example, claw-shaped protrusions for grasping the roller) fornarrowing the opening of the pocket so that the roller inserted into thepocket 110 is held so as not to drop off.

With the above-mentioned structure (the so-called single-split cagestructure) in which the deficit sections 108 a and 108 b are formed inthe pair of rim sections 104 a and 104 b, one each, and the cage 102 hasone crack section 120 in the circumferential direction, when a force isexerted in a direction in which the crack section 120 of thesingle-split cage 102 is expanded or, from a different point of view, ina direction in which both the end faces (the opposed faces of thedeficit sections 108 a and 108 b) of the respective rim sections 104 aand 104 b are separated from each other, the single-split cage 102 isentirely deformed elastically. As a result, the crack section 120 (thedeficit sections 108 a and 108 b) can be expanded; in other words, thediameter of the single-split cage 102 (in short, the rim sections 104 aand 104 b) can be increased. Furthermore, when a force is exerted in adirection in which the crack section 120 is shrunk from this state or,from a different point of view, in a direction in which both the endfaces (the opposed faces of the deficit sections 108 a and 108 b) of therespective rim sections 104 a and 104 b are brought close to each other,the single-split cage 102 is entirely deformed elastically to itsoriginal state before the expansion. As a result, the crack section 120(the deficit sections 108 a and 108 b) can be shrunk to its originalstate; in other words, the diameter of the single-split cage 102 (inshort, the rim sections 104 a and 104 b) can be decreased to itsoriginal diameter (the diameter before the expansion). It is possible toassume a cage configuration in which the diameter of the single-splitcage 102 is decreased and returned to the original diameter (thediameter before the expansion) by using only the elastic restoring forceof the single-split cage 102 generated by relieving the force exerted inthe direction in which the crack section 120 is expanded, withoutexerting a force in the direction in which the crack section 120 of thesingle-split cage 102 is made shrunk, or by exerting a force in thedirection of shrinkage in addition to the elastic restoring force.

Hence, the diameter of the single-split cage 102 can be increased anddecreased as desired, whereby a bearing can be mounted on a rotationshaft having step sections, flange sections, etc. of various sizes.After the bearing is mounted on the rotation shaft, the crack section120 (the deficit sections 108 a and 108 b) of the single-split cage 102is required to be prevented from being expanded again so that thesingle-split cage 102 does not drop off and is not dislocated. In otherwords, the diameter of the pair of rim sections 104 a and 104 b can bemaintained constant and the diameter of the single-split cage 102 can bemaintained steady by preventing the expansion (in short, re-expansion)of the deficit sections 108 a and 108 b.

FIG. 13 shows a configuration example of the single-split cage 102equipped with an engagement section formed of a convex section 112 a anda concave section 112 b fitted to each other as an engagement mechanism.In this case, the one-side split region (the deficit-section-adjacentpillar section 162 as an example) of the deficit-section-adjacent pillarsections 162 and 164 being adjacent to each other with the crack section120 located therebetween and disposed so as to be opposed to each otheris provided with the convex section 112 a, and the other-side splitregion (the deficit-section-adjacent pillar section 164 as an example)is provided with the concave section 112 b. The convex section 112 aprotrudes, while having a predetermined shape and a predetermined size(length), from the face of the deficit-section-adjacent pillar section162 opposed to the deficit-section-adjacent pillar section 164 in thecircumferential direction, and the concave section 112 b is cut off,while having a predetermined shape and a predetermined size (depth inthe circumferential direction), from the inner diameter side to theouter diameter side at the portion of the deficit-section-adjacentpillar section 164 opposed to the deficit-section-adjacent pillarsection 162 so that the concave section 112 b can be fitted on theconvex section 112 a. The shapes and sizes (length and depth) of theconvex section 112 a and the concave section 112 b are not limitedparticularly, and should only be set as desired depending on thematerial, the size (diameter and width) of the single-split cage 102,provided that they can be fitted into each other. Furthermore, theengagement mechanism is not limited to the mechanism formed of theconvex section 112 a and the concave section 112 b capable of beingfitted into each other, but can be modified as necessary to knownvarious kinds of mechanisms, provided that the crack section 120 (thedeficit sections 108 a and 108 b) of the single-split cage 102 can besuppressed from being expanded again.

In this embodiment, the pair of rim sections 104 a and 104 b has thinsections 142 a and 142 b being thin in the radial direction, thediameter of the inner circumferential sections of which is made largerthan that of the inner circumferential sections of the pillar sections106, and also has thick sections 144 a and 144 b being thick in theradial direction, the diameter of which is made smaller than that of thethin sections 142 a and 142 b. Furthermore, the thin sections 142 a and142 b are disposed at portions positioned on the opposite side of thedeficit sections 108 a and 108 b with respect to the center of the innercircumferential sections of the pair of rim sections 104 a and 104 b, inother words, at portions dislocated from the deficit sections 108 a and108 b by 180° in phase in the circumferential direction (the portionsdesignated by 140 a and 140 b in FIG. 13, hereafter referred to as startpoints 140 a and 140 b). Since the thin sections 142 a and 142 b and thethick sections 144 a and 144 b are disposed in the inner circumferentialsections of the pair of rim sections 104 a and 104 b as described above,when a force is exerted in a direction in which the crack section 120 ofthe cage 102 is expanded (in a direction in which both thecircumferential end faces (the opposed faces of the deficit sections 108a and 108 b) of the rim sections 104 a and 104 b are separated from eachother), the thin sections 142 a and 142 b can be elastically deformedsignificantly earlier than the thick sections 144 a and 144 b, wherebythe entire single-split cage 102 can be elastically deformed easily.Hence, the crack section 120 (the deficit sections 108 a and 108 b) canbe expanded easily, that is, the single-split cage 102 can be increasedeasily in diameter.

The sizes, shapes, numbers and disposition intervals of the thinsections 142 a and 142 b and the thick sections 144 a and 144 b are notlimited particularly and can be set as desired, provided that at leastthe thin sections 142 a and 142 b are disposed at the start points 140 aand 140 b of the pair of rim sections 104 a and 104 b.

For example, FIG. 13 shows a configuration of the cage 102 in which thethin sections 142 a and 142 b and the thick sections 144 a and 144 b aredisposed, three respectively. In this case, the thin sections 142 a and142 b are disposed one by one at nearly equal intervals in thecircumferential direction on both sides, starting from the thin sections142 a and 142 b (hereafter referred to as start-point thin sections 142a and 142 b for the sake of convenience) positioned at the start points140 a and 140 b, and the thick sections 144 a and 144 b are disposed oneby one between the thin sections 142 a and 142 b being adjacent in thecircumferential direction. In other words, the thin sections 142 a and142 b and the thick sections 144 a and 144 b are disposed, threerespectively, so as to be arranged alternately in the circumferentialdirection in the inner circumferential sections of the rim sections 104a and 104 b, whereby steps 146 a and 146 b are formed at the boundariesof the thin sections 142 a and 142 b and the thick sections 144 a and144 b adjacent in the circumferential direction. Moreover, the thinsections 142 a and 142 b (the start-point thin sections 142 a and 142 b)are disposed at the start points 140 a and 140 b and in the vicinitiesthereof, and the thick sections 144 a and 144 b (hereafter referred toas deficit-section-adjacent thick sections 144 a and 144 b for the sakeof convenience) are disposed in the vicinities of the deficit sections108 a and 108 b.

Still further, the three thin sections 142 a (the start-point thinsection 142 a) of the rim section 104 a and the three thin sections 142b (the start-point thin section 142 b) of the rim section 104 b aredisposed while respectively having the same phase in the circumferentialdirection; and the three thick sections 144 a (thedeficit-section-adjacent thick section 144 a) of the rim section 104 aand the three thick sections 144 b (the deficit-section-adjacent thicksection 144 b) of the rim section 104 b are also disposed whilerespectively having the same phases in the circumferential direction. Inother words, the thin sections 142 a (the start-point thin section 142a) and the thick sections 144 a (the deficit-section-adjacent thicksection 144 a) are disposed so as to be symmetric with the thin sections142 b (the start-point thin section 142 b) and the thick sections 144 b(the deficit-section-adjacent thick sections 144 b) in thecircumferential direction at both the rim sections 104 a and 104 b.

The thin sections 142 a and 142 b (the start-point thin sections 142 aand 142 b) and the thick sections 144 a and 144 b (thedeficit-section-adjacent thick sections 144 a and 144 b) are disposed inthe inner circumferential regions of the rim sections 104 a and 104 bcontinuously striding over the plurality of pillar sections 106 andpockets 110 (in other words, rollers), and the boundaries of the thinsections 142 a and 142 b and the thick sections 144 a and 144 b adjacentto each other, that is, the steps 146 a and 146 b, are positioned not onthe pillar sections 106 but on the pockets 110 of the rim sections 104 aand 104 b. At the time, the thin sections 142 a and 142 b (thestart-point thin sections 142 a and 142 b) respectively stride over theplurality of pillar sections 106 and pockets 110 (in other words,rollers) continuously while having a constant diameter (the samediameter); and the thick sections 144 a and 144 b (thedeficit-section-adjacent thick sections 144 a and 144 b) alsorespectively stride over the plurality of pillar sections 106 andpockets 110 (in other words, rollers) continuously while having aconstant diameter (the same diameter). More specifically, the thinsections 142 a and 142 b (the start-point thin sections 142 a and 142 b)and the thick sections 144 a and 144 b (the deficit-section-adjacentthick sections 144 a and 144 b) are respectively formed continuouslyalong the predetermined regions while respectively having constantthicknesses in the circumferential direction, and the thin sections 142a and 142 b (the start-point thin sections 142 a and 142 b) are formedcontinuously along the predetermined regions while respectively having athickness smaller than that of the thick sections 144 a and 144 b (thedeficit-section-adjacent thick sections 144 a and 144 b) in the radialdirection.

The start-point thin sections 142 a and 142 b are positioned so that theintermediate portions thereof in the circumferential direction arenearly aligned with the start points 140 a and 140 b. Furthermore,although the deficit-section-adjacent thick sections 144 a and 144 b aredivided into two parts at the deficit sections 108 a and 108 b, in thecase that these two parts are assumed to be one, the thick sections areassumed to be continuous along the predetermined regions.

In this embodiment, the thin sections 142 a and 142 b (the start-pointthin sections 142 a and 142 b) are disposed continuously while stridingover the plurality of pillar sections 106 and pockets 110 (in otherwords, rollers) as described above, whereby when the split section 120is expanded, the stress of the force exerted to the single-split cage102 can be exerted while being distributed to the entire thin sections142 a and 142 b (in particular, the entire start-point thin sections 142a and 142 b) and can thus be relieved. Hence, the stress can beeffectively avoided from being exerted concentratedly to specificportions being limited extremely in the rim sections 104 a and 104 b andthe pillar sections 106.

Furthermore, the thin sections 142 a and 142 b and the thick sections144 a and 144 b are disposed alternately in the inner circumferentialsections of the rim sections 104 a and 104 b, and the steps 146 a and146 b are formed at the boundaries of the thin sections 142 a and 142 band the thick sections 144 a and 144 b being adjacent to each other,whereby the thicknesses of the inner circumferential sections of the rimsections 104 a and 104 b in the radial direction can be prevented frombeing uniform along the entire circumferences and can thus be changed.Hence, for example, even in the case that an inner track is formed intoa concave shape on the outer circumferential face of an inner member (aninner ring, a shaft, etc. being rotatable during use) and thesingle-split cage 102 is used to guide the end faces thereof, the thicksections 144 a and 144 b can be allowed to interfere along the fringe ofthe inner track formed into the concave shape, and the single-split cage102 can be effectively prevented from riding over the outercircumferential face of the inner member. As a result, not only thesingle-split cage 102 but also a bearing can be configured without beinglimited in the configuration of the peripheral sections of the bearing.

Furthermore, the thin sections 142 a and 142 b and the thick sections144 a and 144 b are disposed on the rim sections 104 a and 104 b and donot affect the configuration of the pillar sections 106 particularly.Hence, the pillar sections 106 can be made more slender. In other words,in the case that the same number of rollers are held in the single-splitcage 102 having the same diameter, the pillar sections 106 become moreslender as the roller diameter becomes larger; even in this case, it isnot difficult to expand the crack section 120 (in other words, it is notdifficult to increase the diameter of the single-split cage 102). As aresult, the roller diameter can be made larger without decreasing thenumber of the rollers to be held in the single-split cage 102, and theload capacity of the bearing can be improved.

As described above, the sizes, shapes, numbers and disposition intervalsof the thin sections 142 a and 142 b and the thick sections 144 a and144 b can be set as desired, provided that at least the thin sections142 a and 142 b are disposed at the start points 140 a and 140 b of thepair of rim sections 104 a and 104 b, and the configurations of the thinsections 142 a and 142 b and the thick sections 144 a and 144 b are notlimited to those of this embodiment (FIG. 13).

For example, as in a third embodiment of the present invention shown inFIG. 14, it may be possible to use a configuration in which the thinsections 142 a and 142 b and the thick sections 144 a and 144 b aredisposed, one each, or as in a fourth embodiment of the presentinvention shown in FIG. 15, it may be possible to use a configuration inwhich the thin sections 142 a and 142 b and the thick sections 144 a and144 b are disposed, ten each.

In the third embodiment, as shown in FIG. 14, each one of the thinsections 142 a and 142 b is disposed on the side of the start points 140a and 140 b, and each one of the thick sections 144 a and 144 b isdisposed on the side of the deficit sections 108 a and 108 b so as to becontinuous with the thin sections 142 a and 142 b. In other words, inthe inner circumferential sections of the pair of rim sections 104 a and104 b, only the start-point thin sections 142 a and 142 b and thedeficit-section-adjacent thick sections 144 a and 144 b are disposed onboth the rim sections 104 a and 104 b so as to be symmetric in thecircumferential direction, and the steps 146 a and 146 b are formed atthe boundaries of the start-point thin sections 142 a and 142 b and thedeficit-section-adjacent thick sections 144 a and 144 b. At the time,the steps 146 a and 146 b are positioned not on the pillar sections 106but on the pockets 110 of the rim sections 104 a and 104 b.

Furthermore, in the fourth embodiment, as shown in FIG. 15, the thinsections 142 a and 142 b including the start-point thin sections 142 aand 142 b, ten each in total, are disposed at nearly equal intervals onboth sides in the circumferential direction from the start-point thinsections 142 a and 142 b, and the thick sections 144 a and 144 b aredisposed between the thin sections 142 a and 142 b adjacent to eachother in the circumferential direction, one each, whereby the thicksections 144 a and 144 b including the deficit-section-adjacent thicksections 144 a and 144 b, ten each in total, are disposed. In this case,the thin sections 142 a and 142 b (the start-point thin sections 142 aand 142 b) are disposed so as to be continuous while having a constantdiameter (the same diameter) and striding over one pocket 110 (in otherwords, a roller) and two pillar sections 106 and so as to skip each oneof the pockets 110 (rollers) adjacent to each other on both sides of thepair of rim sections 104 a and 104 b in the circumferential direction.In other words, the boundaries (in other words, the steps 146 a and 146b) of the thin sections 142 a and 142 b (the start-point thin sections142 a and 142 b) and the thick sections 144 a and 144 b (thedeficit-section-adjacent thick sections 144 a and 144 b) are positionedat the portions (on the pillar sections 106 of the rim sections 104 aand 104 b) in which the pair of rim sections 104 a and 104 b isconnected by the pillar sections 106.

As described above, the boundaries (the steps 146 a and 146 b) of thethin sections 142 a and 142 b (the start-point thin sections 142 a and142 b) and the thick sections 144 a and 144 b (thedeficit-section-adjacent thick sections 144 a and 144 b) are positionednot on the pockets 110 but on the pillar sections 106 of the rimsections 104 a and 104 b; hence, in the case that the entiresingle-split cage 102, that is, the rim sections 104 a and 104 b (thethin sections 142 a and 142 b and the thick sections 144 a and 144 b)and the pillar sections 106 are integrally injection molded, the matingfaces of the metal mold thereof are positioned on the cross sections ofthe pillar sections 106, whereby the influence of burrs generated duringmolding can be suppressed in comparison with a case in which theboundaries (the steps 146 a and 146 b) are positioned on the pockets 110in the rim sections 104 a and 104 b as in the second embodiment (FIG.13) and the third embodiment (FIG. 14).

In the above-mentioned second embodiment (FIG. 13) and the thirdembodiment (FIG. 14), it is possible to have a configuration in whichthe boundaries (the steps 146 a and 146 b) are positioned not on thepockets 110 but on the pillar sections 106 of the rim sections 104 a and104 b.

In the single-split cage 102 in which the thin sections 142 a and 142 band the thick sections 144 a and 144 b, three each, are disposed as inthe case of the above-mentioned second embodiment (FIG. 13), aconfiguration example in which the boundaries (the steps 146 a and 146b) thereof are positioned not on the pockets 110 but on the pillarsections 106 of the rim sections 104 a and 104 b is shown in FIG. 16 asa fifth embodiment of the present invention.

The single-split cage 102 according to the second embodiment to thefifth embodiment described above (FIG. 13 to FIG. 16) is capable ofallowing the split section 120 to be expanded easily and sufficientlyand capable of effectively preventing from riding over inner members (aninner ring, a shaft, etc. being rotatable during use) while avoiding thedeterioration in strength and the reduction in the number of rollers tobe held.

Furthermore, in the second embodiment to the fifth embodiment describedabove (FIG. 13 to FIG. 16), the steps 146 a and 146 b are formed at theboundaries of the thin sections 142 a and 142 b (the start-point thinsections 142 a and 142 b) and the thick sections 144 a and 144 b (thedeficit-section-adjacent thick sections 144 a and 144 b) being adjacentto each other in the circumferential direction, and the thin sections142 a and 142 b and the thick sections 144 a and 144 b are arrangedalternately on the inner circumferential portions of the pair of rimsections 104 a and 104 b in the circumferential direction; however,instead of forming the steps 146 a and 146 b at the boundaries, it ispossible to assume a configuration in which the thin sections 142 a and142 b (the start-point thin sections 142 a and 142 b) and the thicksections 144 a and 144 b (the deficit-section-adjacent thick sections144 a and 144 b) are formed continuously.

The configuration in which the thin sections 142 a and 142 b (thestart-point thin sections 142 a and 142 b) and the thick sections 144 aand 144 b (the deficit-section-adjacent thick sections 144 a and 144 b)are formed continuously without steps is shown in FIGS. 17A and 17B as asixth embodiment of the present invention.

In this embodiment, the thin sections 142 a and 142 b and the thicksections 144 a and 144 b are formed continuously without steps such thatthe inner diameter is decreased gradually from the thinnest portions ofthe thin sections 142 a and 142 b to the thickest portions of the thicksections 144 a and 144 b (FIGS. 17A and 17B. Since the thin sections 142a and 142 b and the thick sections 144 a and 144 b are formedcontinuously without steps as described above, the center C1 of theimaginary inner circumferential circle and the center C2 of theimaginary outer circumferential circle obtained by continuing thedeficit sections 108 a and 108 b of the rim sections 104 a and 104 b arein a state of being dislocated from each other, that is, the two circlesare in a state of being eccentric from each other (FIG. 17B). In theconfiguration of this kind of cage 102, the thinnest portions in whichthe thin sections 142 a and 142 b become thinnest in the radialdirection correspond to the start-point thin sections 142 a and 142 b,and the thickest portions in which the thick sections 144 a and 144 bbecome thickest in the radial direction correspond to thedeficit-section-adjacent thick sections 144 a and 144 b.

In this embodiment, the steps 146 a and 146 b (FIG. 13 to FIG. 16) arenot formed at the boundaries of the thin sections 142 a and 142 b andthe thick sections 144 a and 144 b being adjacent to each other in theinner circumferential sections of the rim sections 104 a and 104 b;however, the thicknesses of the inner circumferential sections of therim sections 104 a and 104 b in the radial direction can be preventedfrom becoming uniform along the entire circumferences and can thus bechanged. Hence, for example, even in the case that an inner track isformed into a concave shape on the outer circumferential face of aninner member (an inner ring, a shaft, etc. being rotatable during use)and the single-split cage 102 is used to guide the end faces thereof,any regions of the inner circumferential sections of the rim sections104 a and 104 b extending from the start-point thin sections 142 a and142 b to the deficit-section-adjacent thick sections 144 a and 144 b canbe allowed to interfere along the fringe of the inner track formed intothe concave shape, and the single-split cage 102 can be effectivelyprevented from riding over the outer circumferential face of the innermember. As a result, not only the single-split cage 102 but also abearing can be configured without being limited in the configuration ofthe peripheral sections of the bearing, as in the second embodiment tothe fifth embodiment (FIG. 13 to FIG. 16) described above.

The radial roller bearing cage according to the present invention willbe described below referring to the accompanying drawings. It ispossible to assume that bearings or the like for journaling rotatingsystems in power mechanisms (an automobile transmission as an example)provided for automobiles, railroad vehicles, etc. are used as bearingsin which the radial roller bearing cage according to the presentinvention is incorporated; however, the bearings are not limited tothese bearings.

Such a bearing is equipped with an outer member (for example, an outerring or a housing being maintained in a non-rotating state at all times,or a gear, a roller, etc. being rotatable during use) having acylindrical outer track on the inner circumferential face thereof; and aplurality of radial rollers (a plurality of needles as an example)incorporated so as to be able to roll between the outer circumferentialface (inner track) of the inner member (for example, an inner ring, ashaft, etc. being rotatable during use) disposed on the inner diameterside of the outer member and the outer track. The size of the bearing,the presence or absence of the inner ring, the size (diameter andlength) and the number of the rollers, etc. can be set as desireddepending on the use conditions, the intended use of the bearing, etc.,thereby not limited particularly herein.

In addition, when these rollers roll between the tracks (the outer trackand the inner track), the rollers are held by the bearing cage so as tobe rotatable inside the pockets thereof to prevent the increase inrotational resistance, seizure, etc. caused by the friction due tomutual contact between the rollers. Bearing lubrication (oil lubricationor grease lubrication) may be performed to further effectively preventthe increase in rotational resistance, seizure, etc. In addition, thebearing cage can also be configured as a guide system for all of rollingelement guidance (roller guidance), outer ring guidance and inner ringguidance.

FIG. 18 shows the configuration of a radial roller bearing cage(hereafter simply referred to as a cage) 302 according to a seventhembodiment of the present invention. In this embodiment, it is assumedthat the cage 302 is made of a predetermined elastic material (a resinas an example) and that the whole of the cage (rim sections 304 a and304 b and pillar sections 306 described later) is integrally molded byinjecting the elastic material into a metal mold (injection molding);however, this does not eliminate the possibility of performing moldingusing other known methods. Furthermore, it may be possible that a moldedbody obtained after injection molding is subjected to cutting, grinding,etc. separately to form the cage 302 as a completed product.

The cage 302 is configured so as to be equipped with a pair of circularring sections 304 a and 304 b and a plurality of pillar sections 306.Each of the pair of rim sections 304 a and 304 b has a discontinuousincomplete ring shape (nearly C-shaped), respectively having deficitsections 308 a and 308 b, each at one portion, and the deficit sections308 a and 308 b of the rim sections 104 a and 104 b are disposedcoaxially so as to be opposed to each other with a predeterminedclearance provided therebetween in the axial direction in a state inwhich the deficit sections 308 a and 308 b have the same phase in thecircumferential direction (in a state in which the positions of thedeficit sections 308 a and 308 b in the circumferential direction arecoincident with each other). In other words, the cage 302 has, as anappearance profile, a nearly cylindrical shape (the so-calledsingle-split cage structure) having a single split section 320 in thecircumferential direction. The diameter of the rim section 304 a and therim section 304 b and the distance between the opposed rim sections inthe axial direction should only be set as desired depending on the sizeof the bearing, etc.

The plurality of pillar sections 306 are used to connect the pair of rimsections 304 a and 304 b in the axial direction and to separate theregion between the rim sections 304 a and 304 b in the circumferentialdirection of the rim sections 304 a and 304 b, thereby forming pockets310 for allowing rollers (needles) (not shown) serving as rollingelements to be inserted and held rotatably. In other words, a singlepocket 310 is formed in the space enclosed by the two pillar sections306 being adjacent to each other in the circumferential direction andthe pair of rim sections 304 a and 304 b. Hence, the cage 302 has astructure in which the pillar sections 306 and the pockets 310 aredisposed alternately in the circumferential direction. However, in theregion between the rim sections 304 a and 304 b separated by the twopillar sections 306 (hereafter referred to as deficit-section-adjacentpillar sections 362 and 364) disposed close to both the circumferentialsides of the deficit sections 308 a and 308 b of the rim sections 304 aand 304 b, the crack section 320 is present, and no pocket 310 isformed. Hence, the cage 302 has a structure in which a roller is lackingonly in this region (that is, the crack section 320); in other words,the cage has a structure in which in the regions other than this region,the rollers are inserted into the pockets, one by one, and the rollersare disposed at equal intervals (at equal pitches) in thecircumferential direction.

The size of the pocket 310 formed by the pillar sections 306 should onlybe set depending on the diameter and length of the roller so that theroller can be held so as to be rotatable in the pockets 310, and thenumber of the pockets 310 (the number of the pillar sections 306 from adifferent point of view) should only be set as desired depending on thecapacity (the number of the rollers to be held) of the cage 302. Inaddition, the shape (the surface shape of the circumferentially opposedfaces of the adjacent pillars 306 from a different point of view) of thepocket face (the face making contact with the circumferential face ofthe roller) should only be formed into a concave curved shape (forexample, a concave curved shape having a curvature slightly smaller thanthat of the circumferential face of the roller). In the peripheralsection of the pocket 310, it is possible to provide protruding sections(for example, claw-shaped protrusions for grasping the roller) fornarrowing the opening of the pocket so that the roller inserted into thepocket 310 is held so as not to drop off.

With the above-mentioned structure (the so-called single-split cagestructure) in which the deficit sections 308 a and 308 b are formed inthe pair of rim sections 304 a and 304 b, one each, and the cage 302 hasone crack section 320 in the circumferential direction, when a force isexerted in a direction in which the crack section 320 of the cage 302 isexpanded or, from a different point of view, in a direction in whichboth the end faces (the opposed faces of the deficit sections 308 a and308 b) of the respective rim sections 304 a and 304 b are separated fromeach other, the cage 302 is entirely deformed elastically. As a result,the crack section 320 (the deficit sections 308 a and 308 b) can beexpanded; in other words, the diameter of the cage 302 (in short, therim sections 304 a and 304 b) can be increased. Furthermore, when aforce is exerted in a direction in which the crack section 320 is shrunkfrom this state or, from a different point of view, in a direction inwhich both the end faces (the opposed faces of the deficit sections 308a and 308 b) of the respective rim sections 304 a and 304 b are broughtclose to each other, the cage 302 is entirely deformed elastically toits original state before the expansion. As a result, the crack section320 (the deficit sections 308 a and 308 b) can be shrunk to its originalstate; in other words, the diameter of the cage 302 (in short, the rimsections 304 a and 304 b) can be decreased to its original diameter (thediameter before the expansion). It is possible to assume a cageconfiguration in which the diameter of the cage 302 is decreased andreturned to the original diameter (the diameter before the expansion) byusing only the elastic restoring force of the cage 302 generated byrelieving the force exerted in the direction in which the crack section320 is expanded, without exerting a force in the direction in which thecrack section 320 of the cage 302 is made shrunk, or by exerting a forcein the direction of shrinkage in addition to the elastic restoringforce.

Hence, the diameter of the cage 302 can be made increased and decreasedas desired, whereby a bearing can be mounted on a rotation shaft havingstep sections, flange sections, etc. of various sizes. After the bearingis mounted on the rotation shaft, the crack section 320 (the deficitsections 308 a and 308 b) of the cage 302 is required to be preventedfrom being expanded again so that the cage 302 does not drop off and isnot dislocated. In other words, the diameter of the pair of rim sections304 a and 304 b can be maintained constant and the diameter of the cage302 can be maintained steady by preventing the expansion (in short,re-expansion) of the deficit sections 308 a and 308 b.

FIG. 18 shows a configuration example of the cage 302 equipped with anengagement section formed of a convex section 312 a and a concavesection 312 b fitted to each other as an engagement mechanism. In thiscase, the one side (the deficit-section-adjacent pillar section 362 asan example) of the deficit-section-adjacent pillar sections 362 and 364being adjacent to each other with the crack section 320 locatedtherebetween and disposed so as to be opposed to each other is providedwith a convex section 312 a, and the other side (thedeficit-section-adjacent pillar section 364 as an example) is providedwith a concave section 312 b. The convex section 312 a protrudes, whilehaving a predetermined shape and a predetermined size (length), from theface of the deficit-section-adjacent pillar section 362 opposed to thedeficit-section-adjacent pillar section 364 in the circumferentialdirection, and the concave section 312 b is cut off, while having apredetermined shape and a predetermined size (depth in thecircumferential direction), from the inner diameter side to the outerdiameter side at the portion of the deficit-section-adjacent pillarsection 364 opposed to the deficit-section-adjacent pillar section 362so that the concave section 312 b can be fitted on the convex section312 a. The shapes and sizes (length and depth) of the convex section 312a and the concave section 312 b are not limited particularly, and shouldonly be set as desired depending on the material, the size (diameter andwidth) of the cage 302, provided that they can be fitted into eachother. Furthermore, the engagement mechanism is not limited to themechanism formed of the convex section 312 a and the concave section 312b capable of being fitted into each other, but can be modified asnecessary to known various kinds of mechanisms, provided that the cracksection 320 (the deficit sections 308 a and 308 b) of the cage 302 canbe suppressed from being expanded again.

In this embodiment, the pair of rim sections 304 a and 304 b has thinsections 342 a and 342 b being thin in the radial direction, thediameter of the outer circumferential sections of which is made smallerthan that of the outer circumferential section of the pillar section306, and also has thick sections 344 a and 344 b being thick in theradial direction, the diameter of which is made larger than that of thethin sections 342 a and 342 b. Furthermore, the thin sections 342 a and342 b are disposed at portions positioned on the opposite side of thedeficit sections 308 a and 308 b with respect to the center of the outercircumferential sections of the pair of rim sections 304 a and 304 b, inother words, portions dislocated from the deficit sections 308 a and 308b by 180° in phase in the circumferential direction (the portionsdesignated by 340 a and 340 b in FIG. 18, hereafter referred to as startpoints 340 a and 340 b). Since the thin sections 342 a and 342 b and thethick sections 344 a and 344 b are disposed in the outer circumferentialsections of the pair of rim sections 304 a and 304 b as described above,when a force is exerted in a direction in which the crack section 320 ofthe cage 302 is expanded (in a direction in which both thecircumferential end faces (the opposed faces of the deficit sections 308a and 308 b) of the rim sections 304 a and 304 b are separated from eachother), the thin sections 342 a and 342 b can be elastically deformedsignificantly earlier than the thin sections 342 a and 342 b, wherebythe entire cage 302 can be elastically deformed easily. Hence, the cracksection 320 (the deficit sections 308 a and 308 b) can be expandedeasily, that is, the cage 302 can be increased easily in diameter.

The inner circumferential sections of the pair of rim sections 304 a and304 b are not made smaller or larger in diameter than the innercircumferential sections of the pillar sections 306, and the diameterthereof is set so as to be constant (the same as the inner diameter atthe pillar sections 306) along the entire circumference. In other words,the cage 302 according to this embodiment has a configuration suited asa cage for inner ring guidance.

The sizes, shapes, numbers and disposition intervals of the thinsections 342 a and 342 b and the thick sections 344 a and 344 b are notlimited particularly and can be set as desired, provided that at leastthe thin sections 342 a and 342 b are disposed at the start points 340 aand 340 b of the pair of rim sections 304 a and 304 b.

For example, in FIG. 18, the thin sections 342 a and 342 b are disposedon the sides of the start points 340 a and 340 b, one each, and thethick sections 344 a and 344 b are disposed on the sides of the deficitsections 308 a and 308 b, one each, so as to be disposed continuously tothe thin sections 342 a and 342 b. In other words, on the outercircumferential sections of the pair of rim sections 304 a and 304 b,only the thin sections 342 a and 342 b and the thick sections 344 a and344 b are disposed so as to be symmetric in the circumferentialdirection at both the rim sections 304 a and 304 b, and the steps 346 aand 346 b are formed at the boundaries of the thin sections 342 a and342 b and the thick sections 344 a and 344 b. At the time, the steps 346a and 346 b, that is, the boundaries of the thin sections 342 a and 342b and the thick sections 344 a and 344 b, are positioned at the portions(on the pillar sections 306 of the rim sections 304 a and 304 b) inwhich the pair of rim sections 304 a and 304 b is connected by thepillar sections 106.

The boundaries (the steps 346 a and 346 b) of the thin sections 342 aand 342 b and the thick sections 344 a and 344 b are positioned not onthe pockets 310 but on the pillar sections 306 of the rim sections 304 aand 304 b; hence, in the case that the entire cage 302, that is, the rimsections 304 a and 304 b (the thin sections 342 a and 342 b and thethick sections 344 a and 344 b) and the pillar sections 306 areintegrally injection molded, the mating faces of the metal mold thereforare positioned on the cross sections of the pillar sections 306, wherebythe influence of burrs generated during molding can be suppressed incomparison with a case in which the boundaries (the steps 346 a and 346b) are positioned on the pockets 310 of the rim sections 304 a and 304b. However, it is possible to assume a configuration in which the steps346 a and 346 b are positioned not on the pillar sections 306 but on thepockets 310 of the rim sections 304 a and 304 b.

Still further, the thin section 342 a of the rim section 304 a and thethin section 342 b of the rim section 304 b are disposed while havingthe same phase in the circumferential direction; and the thick section344 a of the rim section 304 a and the thick section 344 b of the rimsection 304 b are also disposed while having the same phase in thecircumferential direction. In other words, the thin section 342 a andthe thick section 344 a are disposed so as to be symmetric with the thinsection 342 b and the thick section 344 b in the circumferentialdirection at both the rim sections 304 a and 304 b.

The thin sections 342 a and 342 b and the thick sections 344 a and 344 bare disposed in the outer circumferential regions of the rim sections304 a and 304 b continuously striding over the plurality of pillarsections 306 and pockets 310 (in other words, rollers), and theboundaries of the thin sections 342 a and 342 b and the thick sections344 a and 344 b, that is, the steps 346 a and 346 b, are positioned onthe pillar sections 306 in the rim sections 304 a and 304 b. At thetime, the thin sections 342 a and 342 b respectively stride over theplurality of pillar sections 306 and pockets 310 (in other words,rollers) continuously while having a constant diameter (the samediameter); and the thick sections 344 a and 344 b also respectivelystride over the plurality of pillar sections 306 and pockets 310 (inother words, rollers) continuously while having a constant diameter (thesame diameter). More specifically, the thin sections 342 a and 342 b andthe thick sections 344 a and 344 b are respectively formed continuouslyalong the predetermined regions while respectively having constantthicknesses in the circumferential direction, and the thin sections 342a and 342 b are formed continuously along the predetermined regionswhile having a thickness smaller than that of the thick sections 344 aand 344 b in the radial direction.

The thin sections 342 a and 342 b are positioned so that theintermediate portions thereof in the circumferential direction arenearly aligned with the start points 340 a and 340 b. Furthermore,although the thick sections 344 a and 344 b are divided into two partsat the deficit sections 308 a and 308 b, in the case that these twoparts are assumed to be one, the thick sections are assumed to becontinuous along the predetermined regions.

In this embodiment, the thin sections 342 a and 342 b are disposedcontinuously while striding over the plurality of pillar sections 306and pockets 310 (in other words, rollers) as described above, wherebywhen the split section 320 is expanded, the stress of the force exertedto the cage 302 can be exerted while being distributed to the entirethin sections 342 a and 342 b and can thus be relieved. Hence, thestress can be effectively avoided from being exerted concentratedly tospecific portions being limited extremely in the rim sections 304 a and304 b and the pillar sections 306.

Furthermore, the thin sections 342 a and 342 b and the thick sections344 a and 344 b are disposed in the outer circumferential sections ofthe rim sections 304 a and 304 b, and the steps 346 a and 346 b areformed at the boundaries of the thin sections 342 a and 342 b and thethick sections 344 a and 344 b being adjacent to each other. As aresult, the thicknesses of the outer circumferential sections of the rimsections 304 a and 304 b in the radial direction can be prevented frombeing uniform along the entire circumferences and can thus be changed.Hence, for example, even in the case that an outer track is formed intoa concave shape on the inner circumferential face of an outer member (anouter ring or a housing being maintained in a non-rotating state at alltimes, or a gear, a roller, etc. being rotatable during use) and thecage 302 is used to guide the end faces thereof, the thick sections 344a and 344 b can be allowed to interfere along the fringe of the outertrack formed into the concave shape, and the cage 302 can be effectivelyprevented from riding over the inner circumferential face of the outermember. As a result, not only the cage 302 but also a bearing can beconfigured without being limited in the configuration of the peripheralsections of the bearing.

Furthermore, the thin sections 342 a and 342 b and the thick sections344 a and 344 b are disposed on the rim sections 304 a and 304 b and donot affect the configuration of the pillar sections 306 particularly.Hence, the pillar sections 306 can be made more slender. In other words,in the case that the same number of rollers are held in the cage 302having the same diameter, the pillar sections 306 become more slender asthe roller diameter becomes larger; even in this case, it is notdifficult to expand the crack section 320 (in other words, it is notdifficult to increase the diameter of the cage 302). As a result, theroller diameter can be made larger without decreasing the number of therollers to be held in the cage 302, and the load capacity of the bearingcan be improved.

As described above, the sizes, shapes, numbers and disposition intervalsof the thin sections 342 a and 342 b and the thick sections 344 a and344 b can be set as desired, provided that at least the thin sections342 a and 342 b are disposed at the start points 340 a and 340 b of thepair of rim sections 304 a and 304 b, and the configurations of the thinsections 342 a and 342 b and the thick sections 344 a and 344 b are notlimited to those of this embodiment (FIG. 18).

For example, it may be possible to use a cage configuration in which thethin sections and the thick sections are disposed, two or more each(three each as an example). In this case, it is preferable that the thinsections are disposed one by one at nearly equal intervals on both sidesin the circumferential direction from the thin sections positioned atthe start points 340 a and 340 b, and that the thick sections aredisposed one by one between the thin sections adjacent to each other inthe circumferential direction. In other words, a configuration shouldonly be used in which a plurality of thin sections and a plurality ofthick sections (the same number as an example) are arranged alternatelyone by one in the circumferential direction on the outer circumferentialsections of the rim sections 304 a and 304 b, and steps are formed atthe boundaries between the thin sections and the thick sections adjacentto each other in the circumferential direction. In this case, theplurality of thin sections of the rim section 304 a and the plurality(as many as the thin sections of the rim section 304 a) of thin sectionsof the rim section 304 b are disposed while having the same phase in thecircumferential direction, and the plurality (as many as the thinsections of the rim section 304 a) of thick sections of the rim section304 a and the plurality (as many as the thick sections (thin sections)of the rim section 304 a) of thick sections of the rim section 304 b arealso disposed while having the same phase in the circumferentialdirection. In other words, the thin sections and the thick sectionsshould only be disposed so as to be symmetric in the circumferentialdirection at both the rim sections 304 a and 304 b.

Furthermore, in the above-mentioned first embodiment (FIG. 18), theouter circumferential sections of the pair of rim sections 304 a and 304b are made smaller in diameter than the outer circumferential sectionsof the pillar sections 306, whereby the thin sections 342 a and 342 bare made thin in the radial direction; furthermore, it is possible tohave a configuration in which the inner circumferential sections of thepair of rim sections 304 a and 304 b are made larger in diameter thanthe inner circumferential sections of the pillar sections 306, wherebythe thin sections 342 a and 342 b are made thinner than the thicksections 344 a and 344 b on both the outer diameter sides and the innerdiameter sides in the radial direction.

By making the outer circumferential sections of the pair of rim sections304 a and 304 b smaller in diameter than the outer circumferentialsections of the pillar sections 306 and by making the innercircumferential sections thereof larger in diameter than the innercircumferential sections of the pillar sections 306 as described above,the configuration of the cage 302 having the thin sections 342 a and 342b being dented on both the outer diameter sides and the inner diametersides in the radial direction and made thinner than the thick sections344 a and 344 b is obtained and shown in FIG. 19 as an eighth embodimentof the present invention. The cage 302 according to this embodiment hasa configuration suited as a cage for rolling element guidance (rollerguidance).

In this case, the pair of rim sections 304 a and 304 b is configured inwhich the inner circumferential sections thereof are increased indiameter uniformly (along the same width (circumferential range) andcontinuously formed while having a constant diameter (the same diameter)so that the inner circumferential sections correspond to the decreaseddiameter portions of the outer circumferential sections, that is, havethe same phase in the circumferential direction. At the time, thedecreased diameter portion of the outer circumferential section and theincreased diameter portion of the inner circumferential section (thatis, the thin section 342 a) of the rim section 304 a and the decreaseddiameter portion of the outer circumferential portion and the increaseddiameter portion of the inner circumferential section (that is, the thinsection 342 b) of the rim section 304 b are both disposed so as to havethe same phase in the circumferential direction. Hence, as in theseventh embodiment (FIG. 18) described above, the thin section 342 a issymmetric with the thick section 344 a and the thin section 342 b issymmetric with the thick section 344 b in the circumferential directionat both the rim sections 304 a and 304 b. At the time, the steps 346 aand 346 b are formed at the boundaries of the thin sections 342 a and342 b and the thick sections 344 a and 344 b not only in the outercircumferential sections but also in the inner circumferential sectionsof the pair of rim sections 304 a and 304 b, and these steps 346 a and346 b are positioned at portions (on the pillar sections 306 of the rimsections 304 a and 304 b) where the pair of rim sections 304 a and 304 bis connected by the pillar sections 306 while having the same phase inthe circumferential direction (however, the steps can also be positionedon the pockets 310 of the rim sections 304 a and 304 b).

The decreased diameter of the outer circumferential sections and theincreased diameter of the inner circumferential sections of the pair ofrim sections 304 a and 304 b are not limited particularly; the amount ofdiameter decrease and the amount of diameter increase may have the samedimension (in a state in which the thick sections 344 a and 344 b aredented in the radial direction on both the outer diameter sides and theinner diameter sides by the same dimension), or the amount of diameterdecrease and the amount of diameter increase may have differentdimensions (in a state in which the thick sections 344 a and 344 b aredented in the radial direction on both the outer diameter sides and theinner diameter sides by different dimensions).

Furthermore, in the case of a cage configuration in which the thinsections 342 a and 342 b and the thick sections 344 a and 344 b aredisposed, two or more each, the inner circumferential sections of therim sections 304 a and 304 b should only be respectively increased indiameter so as to correspond to the respective diameter-decreaseportions of the outer circumferential sections (so as to have the samephase in the circumferential direction). Hence, the thin sections 342 aand 342 b and the thick sections 344 a and 344 b are disposedalternately on the inner circumferential sections of the rim sections304 a and 304 b as in the case of the outer circumferential sections,whereby the steps 346 a and 346 b are formed at the boundaries of thethin sections 342 a and 342 b and the thick sections 344 a and 344 badjacent to each other.

Moreover, as in cages 302 according to a ninth embodiment of the presentinvention shown in FIG. 20, according to a tenth embodiment of thepresent invention shown in FIG. 21, and according to an 11th embodimentof the present invention shown in FIG. 22, the thin sections 342 a and342 b can be configured so as to be formed continuously while thedecreased diameter portions of the outer circumferential sections andthe increased diameter portions of the inner circumferential sections ofthe rim sections 304 a and 304 b are different in phase in thecircumferential direction (along different widths (circumferentialranges). In other words, in this case, the configuration of the steps346 a and 346 b formed at the boundaries of the thin sections 342 a and342 b and the thick sections 344 a and 344 b on the outer diameter sidesof the rim sections 304 a and 304 b in the radial direction is differentfrom the configuration thereof on the inner diameter sides of the rimsections in the circumferential positions thereof (the phase in thecircumferential direction). The decreased diameter portions of the outercircumferential sections and the increased diameter portions of theinner circumferential sections of the rim sections 304 a and 304 bshould only be decreased or increased in diameter uniformly and formedcontinuously while each having a constant diameter (the same diameter)so that the decreased diameter portion of the outer circumferentialsection and the increased diameter portion of the inner circumferentialsection of the rim section 304 a and the decreased diameter portion ofthe outer circumferential section and the increased diameter portion ofthe inner circumferential section of the rim section 304 b have the samephase in the circumferential direction. In addition, the steps 346 a and346 b should only be positioned at portions (on the pillar sections 306of the rim sections 304 a and 304 b) where the pair of rim sections 304a and 304 b are connected by the pillar sections 306 while having thesame phase in the circumferential direction in both the rim sections 304a and 304 b (however, the steps can also be positioned on the pockets310 of the rim sections 304 a and 304 b).

In the ninth embodiment (FIG. 20), in order that the intermediateportions of the thin sections 342 a and 342 b in the circumferentialdirection are disposed so as to be nearly aligned with the start points340 a and 340 b, the outer circumferential sections of the rim sections304 a and 304 b are continuously decreased in diameter in thecircumferential direction so as to have a predetermined width (along anouter circumferential region striding over the four pillar sections 306and the three pockets 310 (in other words, rollers) as an example), andthe inner circumferential sections of the rim sections 304 a and 304 bare continuously increased in diameter so as to have a width (along aninner circumferential region striding over the six pillar sections 306and the five pockets 310 (in other words, rollers) as an example) largerthan that of the portions in which the outer circumferential sectionsare decreased in diameter in the circumferential direction. In thiscase, the circumferential ranges in which the decreased diameterportions of the outer circumferential sections are superimposed on theincreased diameter portions of the inner circumferential sections of therim sections 304 a and 304 b in the circumferential direction, morespecifically, the circumferential ranges being made thinner (decreasedin thickness) than the thick sections 344 a and 344 b on both the outerdiameter sides and the inner diameter sides in the radial direction areused as the thin sections 342 a and 342 b, and in the circumferentialranges in which the increased diameter portions of the innercircumferential sections are located beyond the decreased diameterportions of the outer circumferential sections in the circumferentialdirection, intermediate thick sections 348 a and 348 b being madethinner (decreased in thickness) than the thick sections 344 a and 344 bonly on the inner diameter sides in the radial direction are formed.Hence, in the inner circumferential sections of the rim sections 304 aand 304 b, steps 346 a and 346 b are formed at the boundaries of theintermediate thick sections 348 a and 348 b and the thick sections 344 aand 344 b.

Provided that the increased diameter portions of the innercircumferential sections of the rim sections 304 a and 304 b are formedcontinuously so as to have a width larger than that of the decreaseddiameter portions of the outer circumferential section in thecircumferential direction and that the increased diameter portions aresuperimposed on the decreased diameter portions in the circumferentialdirection, the circumferential width of the decreased diameter portionsof the outer circumferential section may be set as desired. For example,as in the tenth embodiment of the present invention shown in FIG. 21,the cage 302 can have a configuration in which the inner circumferentialsections of the rim sections 304 a and 304 b are continuously increasedin diameter uniformly along the entire circumferences thereof. In thiscase, in the inner circumferential sections of the rim sections 304 aand 304 b, the thin sections 342 a and 342 b and the thick sections 344a and 344 b are formed continuously without steps.

With the above-mentioned configuration of the thin sections 342 a and342 b, for example, when a bearing is mounted on a rotation shaft havingstep sections, flange sections, etc. having various sizes, thevicinities of the inner diameter sides of the start points 340 a and 340b of the rim sections 304 a and 304 b that serve as the tension sideswhen the crack section 320 (the deficit sections 308 a and 308 b) isexpanded and the cage 302 (in short, the rim sections 304 a and 304 b)in increased in diameter can be made wider in the circumferentialdirection and thinner (decreased in thickness) than the vicinities ofthe outer diameter sides thereof. In other words, the circumferentialwidths (circumferential ranges) to be made thin in the vicinities on theouter diameter sides of the start points 340 a and 340 b of the rimsections 304 a and 304 b can be made as small as possible in comparisonwith those in the vicinities on the inner diameter sides (in otherwords, the amount to be decreased in thickness can be made as small aspossible). Hence, even in the case that the cage 302 is used for endface guidance, the areas of the axial end faces of the rim sections 304a and 304 b serving as the guide sections thereof can be obtainedsecurely, the continuity on the outer diameter sides can be raised, andthe stability during outer diameter guidance can be improved.

On the other hand, in the 11th embodiment (FIG. 22), in order that theintermediate portions of the thin sections 342 a and 342 b in thecircumferential direction are disposed so as to be nearly aligned withthe start points 340 a and 340 b, the outer circumferential sections ofthe rim sections 304 a and 304 b are continuously decreased in diameterin the circumferential direction so as to have a predetermined width(along an outer circumferential region striding over the six pillarsections 306 and the five pockets 310 (in other words, rollers) as anexample), and the inner circumferential sections of the rim sections 304a and 304 b are continuously increased in diameter so as to have a width(along an inner circumferential region striding over the four pillarsections 306 and the three pockets 310 (in other words, rollers) as anexample) smaller than that of the portions in which the outercircumferential sections are decreased in diameter in thecircumferential direction. In other words, the circumferential ranges inwhich the decreased diameter portions of the outer circumferentialsections are superimposed on the increased diameter portions of theinner circumferential sections in the circumferential direction are madethinner (decreased in thickness) than the thick sections 344 a and 344 bon both the outer diameter sides and the inner diameter sides in theradial direction, and the circumferential ranges in which the decreaseddiameter portions of the outer circumferential sections are locatedbeyond the increased diameter portions of the inner circumferentialsections in the circumferential direction are made thinner (decreased inthickness) than the thick sections 344 a and 344 b only on the outerdiameter sides in the radial direction. In other words, this embodimentis common to the above-mentioned ninth embodiment (FIG. 20) with respectto the circumferential range in which the decreased diameter portions ofthe outer circumferential sections are superimposed on the increaseddiameter portions of the inner circumferential sections in thecircumferential direction, but is different from the ninth embodiment(in which the intermediate thick sections 348 a and 348 b are formed) inwhich the circumferential ranges are made thinner than the thicksections 344 a and 344 b only on the inner diameter sides in the radialdirection in that the circumferential ranges are made thinner than thethick sections 344 a and 344 b only on the outer diameter sides in theradial direction.

In this case, provided that the decreased diameter portions of the outercircumferential sections of the rim sections 304 a and 304 b are formedcontinuity while having a width larger than that of the increaseddiameter portions of the inner circumferential sections in thecircumferential direction and that the decreased diameter portions aresuperimposed on the increased diameter portions in the circumferentialdirection, the circumferential width of the decreased diameter portionswith respect to the increased diameter portions of the innercircumferential sections can be set as desired. For example, it ispossible to use a configuration in which the outer circumferentialsections of the rim sections 304 a and 304 b are continuously increasedin diameter uniformly along the entire circumferences (in other words, aconfiguration in which the thin sections 342 a and 342 b and the thicksections 344 a and 344 b are formed continuously without steps on theouter circumferential sections of the rim sections 304 a and 304 b).

With the above-mentioned configuration of the thin sections 342 a and342 b, the vicinities of the outer diameter sides of the start points340 a and 340 b of the rim sections 304 a and 304 b can be made wider inthe circumferential direction and thinner (decreased in thickness) thanthe vicinities of the inner diameter sides thereof. In other words, thecircumferential widths (circumferential ranges) to be made thin in thevicinities on the inner diameter sides of the start points 340 a and 340b of the rim sections 304 a and 304 b can be made as small as possiblein comparison with those in the vicinities on the outer diameter sides(in other words, the amount to be decreased in thickness can be made assmall as possible). Hence, for example, even in the case that the cage302 (in short, the rim sections 304 a and 304 b) is required todecreased in diameter when a bearing is mounted in a hole section or thelike having steps, since the vicinities of the outer diameter sides ofthe start points 340 a and 340 b that serve as the tension sides at thetime are made wider in the circumferential direction and thinner(decreased in thickness) than the vicinities of the inner diameter sidesthereof, the cage 302 can be decreased in diameter smoothly.

In the above-mentioned ninth embodiment to the 11th embodiment (FIG. 20to FIG. 22), the sizes, shapes, numbers and disposition intervals of thethin sections 342 a and 342 b (the decreased diameter portions of theouter circumferential sections and the increased diameter portions ofthe inner circumferential sections) can be set as desired (as in theabove-mentioned seventh embodiment).

For example, in these embodiments, on the rim sections 304 a and 304 b,the decreased diameter portion of the outer circumferential section andthe increased diameter portion of the inner circumferential section areeach disposed, only at one portion, and the thin sections 142 a and 142b are disposed, one each; however, it is possible to use a configurationin which the decreased diameter portions of the outer circumferentialsections and the increased diameter portions of the innercircumferential sections are respectively formed at pluralities ofportions, whereby a plurality of thin sections are disposed. This kindof configuration is shown as a 12th embodiment of the present invention.

FIG. 23 shows an example of the configuration of a cage 302 in which thedecreased diameter portions at the third portions are formed on each ofthe outer circumferential sections of the rim sections 304 a and 304 b,and the increased diameter portions are formed on each of the innercircumferential sections thereof, whereby the thin sections 342 a and342 b are disposed. In this case, the vicinities on the outer diametersides of the start points 340 a and 340 b are decreased in diametercontinuously while having a predetermined width in the circumferentialdirection (along the outer circumferential regions striding over twopillar sections 306 and one pocket 310 (in other words, a roller), as anexample), and on both sides of the decreased diameter portions in thecircumferential direction (hereafter referred to as start pointdecreased diameter portions) and at a predetermined interval (an outercircumferential region striding over two pillar sections 306 and onepocket 310, as an example), the decreased diameter portions that areformed by continuously decreasing in diameter the outer circumferentialsections of the rim sections 304 a and 304 b while having the same widthas that of the start point decreased diameter portions in thecircumferential direction, one on each side. In addition, the vicinitieson the inner diameter sides of the start points 340 a and 340 b areincreased in diameter continuously while having a width (the same widthas that of the increased diameter portions of the inner circumferentialsections of the rim sections 304 a and 304 b) according to theabove-mentioned 11th embodiment (FIG. 22) as an example) larger thanthat of the start point decreased diameter portions in thecircumferential direction, and on both sides of the increased diameterportions in the circumferential direction (hereafter referred to asstart point increased diameter portions) and at a predetermined interval(an inner circumferential region striding over two pillar sections 306and one pocket 310, as an example), the increased diameter portions thatare formed by continuously increasing in diameter the innercircumferential sections of the rim sections 304 a and 304 b whilehaving the same width as that of the start point increased diameterportions in the circumferential direction, one on each side.

More specifically, in this embodiment, the decreased diameter portionsof the outer circumferential sections and the increased diameterportions of the inner circumferential sections of the rim sections 304 aand 304 b are disposed so as to be distributed to both sides of thecenters of the start points 340 a and 340 b in the circumferentialdirection. In other words, thinned sections made thin by decreasing indiameter the rim sections 304 a and 304 b on the outer diameter sides orby increasing in diameter the rim sections on the inner diameter sidesthereof are disposed so as to be distributed in the circumferentialdirection. Hence, also in this embodiment, on the rim sections 304 a and304 b, intermediate thick sections 348 a and 348 b are formed atportions that are made thinner (decreased in thickness) than the thicksections 344 a and 344 b only on the inner diameter sides in the radialdirection, and in the inner circumferential sections of the rim sections304 a and 304 b, steps 346 a and 346 b are formed at the boundaries ofthe intermediate thick sections 348 a and 348 b and the thick sections344 a and 344 b (as in the above-mentioned ninth embodiment (FIG. 20)).

The disposition number of the decreased diameter portions of the outercircumferential sections and that of the increased diameter portions ofthe inner circumferential sections (the disposition number of thethinned sections on the outer diameter side and that on the innerdiameter side) are not limited particularly and can be set as desireddepending on the size, material, etc. of the cage 302; furthermore, thenumber of the decreased diameter portions and that of the increaseddiameter portion may be the same or different.

In addition, the decreased diameter of the decreased diameter portionsof the outer circumferential sections and the increased diameter of theincreased diameter portions of the inner circumferential sections arenot limited particularly, and diameter decrease and diameter increasemay be performed by the same dimension (in a state of being dented bythe same dimension in the radial direction on both the outer diametersides and the inner diameter sides from the thick sections 344 a and 344b (a state in which the thickness is decreased by the same amount)), ordiameter decrease and diameter increase may be performed by differentdimensions (in a state of being dented by different dimensions in theradial direction on the outer diameter sides and the inner diametersides from the thick sections 344 a and 344 b (a state in which thethickness is decreased by different amounts)). For example, in the startpoint decreased diameter portions and the start point increased diameterportions, the rim sections 304 a and 304 b are decreased in diameterfrom the outer diameter sides and increased in diameter from the innerdiameter sides (decreased in thickness on both the outer diameter sidesand the inner diameter sides) so as to be made thin; hence, the amountsto be decreased in thickness on the outer diameter sides and the innerdiameter sides are limited to some extent in consideration of thestrength of the rim sections 304 a and 304 b themselves. For thisreason, by making the amounts to be decreased in thickness at the startpoint decreased diameter portions and the start point increased diameterportions small and by making the amounts to be decreased in thickness atthe decreased diameter portions and the increased diameter portions onboth sides of these in the circumferential direction larger than thoseof the start point decreased diameter portions and the start pointincreased diameter portions, the diameter increase performance (theexpandability of the crack section 320 (the deficit sections 308 a and308 b) from a different point of view) of the cage 302 (in short, therim sections 304 a and 304 b) can be obtained securely, and the strengthof the cage 302 can also be obtained securely.

More specifically, with this embodiment, while the diameter increaseperformance of the cage 302 is improved and while an optimal openingamount is securely obtained, the strength of the cage 302 can beimproved at the same time.

Furthermore, in the seventh embodiment to the 12th embodiment (FIG. 18to FIG. 23) described above, a configuration is used in which the steps346 a and 346 b are formed at the boundaries of the thin sections 342 aand 342 b and the thick sections 344 a and 344 b, and the thin sections342 a and 342 b and the thick sections 344 a and 344 b are disposed onthe outer circumferential sections of the pair of rim sections 304 a and304 b or on the inner circumferential sections thereof in addition tothe outer circumferential sections; however, it is possible to assume aconfiguration in which the thin sections 342 a and 342 b and the thicksections 344 a and 344 b are formed continuously without forming thesteps 346 a and 346 b at the boundaries.

This configuration in which the thin sections 342 a and 342 b and thethick sections 344 a and 344 b are formed continuously without formingsteps is shown in FIG. 24 as a 13th embodiment of the present invention.The cage 302 according to this embodiment has a configuration suited forthe cage for outer ring guidance.

In this embodiment, the pair of rim sections 304 a and 304 b aredisposed so as to be opposed to each other in a state in which thecenters of the inner circumferential sections thereof (imaginary innercircumferential circles formed by continuously forming the deficitsections 308 a and 308 b of the rim sections 304 a and 304 b) are madeeccentric with respect to the rotation axis (equivalent to the center ofan imaginary circle (pitch circle) formed by connecting the centers ofthe rollers held in the respective pockets) of the cage 302 to theopposite sides (the sides of the portions (the start point sections 340a and 340 b) dislocated by 180° in phase from the deficit sections 308 aand 308 b in the circumferential direction).

In this case, the pair of rim sections 304 a and 304 b has aconfiguration formed of thin sections 342 a and 342 b, the innercircumferential sections of which are made larger in diameter than theinner circumferential sections of the pillar sections 306 so that thethin sections are made thinner in the radial direction, and thicksections 344 a and 344 b made smaller in diameter than the thin sections342 a and 342 b and made thicker in the radial direction. Furthermore,at the portions (the start points 340 a and 340 b) positioned on theopposite sides of the deficit sections 308 a and 308 b with respect tothe centers of the inner circumferential sections of the pair of rimsections 304 a and 304 b, the thin sections 342 a and 342 b aredisposed, and the thin sections 342 a and 342 b and the thick sections344 a and 344 b are gradually decreased in inside diameter from thethinnest portions of the thin sections 342 a and 342 b and continued tothe thickest portions of the thick sections 344 a and 344 b withoutsteps.

In this embodiment, in the inner circumferential sections of the rimsections 304 a and 304 b, the steps 346 a and 346 b (FIG. 18 to FIG. 23)are not formed at the boundaries of the thin sections 342 a and 342 band the thick sections 344 a and 344 b; however, the thicknesses of theinner circumferential sections of the rim sections 304 a and 304 b inthe radial direction can be prevented from being uniform along theentire circumferences and can thus be changed. Hence, for example, evenin the case that an inner track is formed into a concave shape on theouter circumferential face of an inner member (an inner ring, a shaft,etc. being rotatable during use) and the cage 302 is used to guide theend faces thereof, any regions of the inner circumferential sections ofthe rim sections 304 a and 304 b extending from the thin sections 342 aand 342 b to the thick sections 344 a and 344 b can be allowed tointerfere along the fringe of the inner track formed into the concaveshape, and the cage 302 can be effectively prevented from riding overthe outer circumferential face of the inner member. As a result, notonly the cage 302 but also a bearing can be configured without beinglimited in the configuration of the peripheral sections of the bearing,as in the seventh embodiment to the 12th embodiment (FIG. 18 to FIG. 20)described above.

In this embodiment, the inner circumferential sections of the pair ofrim sections 304 a and 304 b are configured so as to be made eccentricwith respect to the rotation axis of the cage 302; however, for example,it is possible to use a configuration wherein in a state in which thecenters of the outer circumferential sections of the pair of rimsections 304 a and 304 b are made eccentric with respect to the rotationaxis of the cage 302 toward the deficit sections (on the opposite sidesof the start point sections), the rim sections are disposed so as to beopposed to each other. In this case, the pair of rim sections 304 a and304 b is configured so as to be formed of the thin sections, thediameter of which is made smaller in diameter than that of the outercircumferential sections of the pillar sections 306, and the thicksections made larger in diameter than the thin sections and made thickerin the radial direction. Moreover, in the portions (the start pointsections 340 a and 340 b) positioned on the opposite sides of thedeficit sections 308 a and 308 b with respect to the centers of theouter circumferential sections of the pair of rim sections 304 a and 304b, a configuration should only be used in which the thin sections aredisposed, and the thin sections and the thick sections are graduallydecreased in inner diameter from the thinnest portions of the thinsections and continued to the thickest portions of the thick sectionswithout steps.

Still further, a configuration may be used in which both the innercircumferential sections and the outer circumferential section of thepair of rim sections 304 a and 304 b are made eccentric with respect tothe rotation axis of the cage 302, the centers of the innercircumferential sections are made eccentric with respect to the rotationaxis of the cage 302 and positioned on the sides of the start pointsections 340 a and 340 b, and the centers of the outer circumferentialsections are made eccentric with respect to the rotation axis of thecage 302 and positioned toward the deficit sections 308 a and 308 b.

With the cages 302 according to the seventh embodiment to the 13thembodiment (FIG. 18 to FIG. 24) according to the present inventiondescribed above, the crack section 320 can be expanded easily andsufficiently while avoiding reduction in strength and decrease in thenumber of rollers to be held; in addition, the cage can be preventedeffectively from riding over track members (the outer circumferentialface of an inner member (an inner ring, a shaft, etc. being rotatableduring use) and the inner circumferential face of an outer member (anouter ring or a housing being maintained in a non-rotating state at alltimes or a gear, a roller, etc. being rotatable during use)).

The present invention is not limited to the above-mentioned embodimentsbut can be modified, improved, etc. as necessary, and theabove-mentioned embodiments and modified examples can be combined andapplied in implementable ranges.

For example, the single-split cages according to the second to 13thembodiments may be configured so as to have the split section describedin the first embodiment, and the present invention is applicable to thesingle-split cages of the double-row type described referring to FIG. 11and FIG. 12.

Although the present application has been described in detail referringto the specific embodiments, it is obvious to those skilled in the artthat the various changes and modifications can be made without departingfrom the spirit and scope of the present invention.

The present application is based on Japanese Patent Application (No.2010-205691) filed on Sep. 14, 2010, Japanese Patent Application (No.2010-257211) filed on Nov. 17, 2010, Japanese Patent Application (No.2011-141439) filed on Jun. 27, 2011, Japanese Patent Application (No.2011-172595) filed on Aug. 8, 2011, Japanese Patent Application (No.2011-172599) filed on Aug. 8, 2011, Japanese Patent Application (No.2011-182771) filed on Aug. 24, 2011 and Japanese Patent Application (No.2011-192973) filed on Sep. 5, 2011, and the contents thereof are hereinincorporated by reference.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

-   -   2 single-split cage    -   2 p pocket    -   4, 6 circular ring section    -   8 pillar section    -   10 split section    -   10 a one-side split region    -   10 b other-side split region    -   30 diameter-increase restricting concave section    -   32 diameter-increase restricting convex section    -   Sa one-side split face    -   Sb other-side split face

1. A single-split cage comprising: a pair of circular ring sectionshaving a circular ring shape and being disposed so as to be opposed toeach other; a plurality of pillar sections continuously extendingbetween the circular ring sections and arranged at predeterminedintervals in the circumferential direction; and a plurality of pocketsformed in the portions enclosed by the pair of circular ring sectionsand the plurality of pillar sections and at predetermined intervals inthe circumferential direction, wherein: in the single-split cage, asplit section for splitting the cage at one portion in thecircumferential direction thereof in a direction being crosswise to thecircumferential direction is provided; the split section is formed atregions extending between the pockets adjacent to each other in thecircumferential direction, and at the circumferential center positionbetween these pockets, a one-side split face and the other-side splitface formed by splitting the regions are disposed so as to be opposed inthe circumferential direction; engagement sections being mutuallyengageable are respectively provided on the one-side split face and theother-side split face, and these engagement sections are disposed so asto be opposed to each other in the circumferential direction; and in astate in which the engagement sections of both the one-side split faceand the other-side split face are mutually engaged, predeterminedclearances are formed between the one-side split face and the other-sidesplit face and between the engagement sections.
 2. The single-split cageaccording to claim 1, wherein: on the one-side split face, as theengagement sections, a plurality of one-side convex sections protrudingtoward the other-side split face and a one-side concave section formedby denting the area between these one-side convex sections are provided;on the other-side split face, as the engagement sections, a plurality ofother-side concave sections with which the plurality of one-side convexsections are engageable and an other-side convex section protrudingtoward the one-side split face between the other-side concave sectionsand engageable with the one-side concave section are provided; in astate in which the engagement sections of both the one-side split faceand the other-side split face are engaged with each other, predeterminedclearances are formed respectively between the one-side convex sectionand the other-side convex section and between the one-side concavesection and the other-side convex section; and in the clearances, theclearances between the mutual engagement sections in the circumferentialdirection are set so as to be smaller than the clearance between theone-side split face and the other-side split face in the circumferentialdirection.
 3. The single-split cage according to claim 2, wherein: in astate in which both the engagement sections of both the one-side splitface and the other-side split face are engaged with each other, theclearance between the one-side split face and the other-side split facein the circumferential direction and the clearance between theengagement sections in the circumferential direction are set so as tosatisfy the relationship of:A>B=C, wherein the clearance formed between the one-side split face andthe other-side split face is A; the clearance formed between theone-side convex section and the other-side concave section is B; and theclearance formed between the one-side concave section and the other-sideconvex section is C.
 4. The single-split cage according to claim 2 or 3,wherein: in a state in which both the engagement sections of theone-side split face and the other-side split face are engaged with eachother, the mutual clearances between the engagement sections in thedirection perpendicular to the circumferential direction are set so asto satisfy the relationship of:D>E, wherein the clearance formed between the one-side convex sectionand the other-side concave section is D; and the clearance formedbetween the one-side concave section and the other-side convex sectionis E.
 5. The single-split cage according to claim 2, wherein: on theone-side split face, diameter-increase restricting concave sections areformed on the axial outsides of the plurality of one-side convexsections; on the other-side split face, diameter-increase restrictingconvex sections capable of being engaged with the diameter-increaserestricting concave sections are formed on the axial outsides of theplurality of the other-side concave section; and the axial side faces ofthe diameter-increase restricting concave section and thediameter-increase restricting convex section, opposed to each other, areformed into a tapered shape so as to make contact with each other whenthe split section is expanded in the circumferential direction.
 6. Thesingle-split cage according to claim 5, wherein: the clearance betweenthe diameter-increase restricting concave section and thediameter-increase restricting convex section, formed in a directionperpendicular to the circumferential direction, is larger than theclearance between the one-side concave section and the other-side convexsection, formed in a direction perpendicular to the circumferentialdirection.
 7. A single-split cage comprising: a pair of circular ringsections having a circular ring shape and being disposed so as to beopposed to each other; a plurality of pillar sections continuouslyextending between the circular ring sections and arranged atpredetermined intervals in the circumferential direction; and aplurality of pockets formed in the portions enclosed by the pair ofcircular ring sections and the plurality of pillar sections and atpredetermined intervals in the circumferential direction, wherein: inthe single-split cage, a split section for splitting the cage at oneportion in the circumferential direction thereof in a direction beingcrosswise to the circumferential direction is provided; and in the pairof circular ring sections, the thickness of the start point sectionsthereof in the radial direction, dislocated from the split section by180° in phase in the circumferential direction, is formed so as to besmaller than the thickness in the vicinity of the split section in theradial direction.
 8. The single-split cage according to claim 7,wherein: the pair of circular ring sections have thin sections and thicksections being different in thickness in the radial direction, the thinsections are positioned at the start point sections, the thick sectionsare positioned in the vicinity of the split section; and the boundariesof the thin sections and the thick sections are positioned on thepockets.
 9. The single-split cage according to claim 7, wherein: thepair of circular ring sections has thin sections and thick sectionsbeing different in thickness in the radial direction, the thin sectionsare positioned at the start point sections, the thick sections arepositioned in the vicinity of the split section; and the boundaries ofthe thin sections and the thick sections are positioned on the pillarsections.
 10. A single-split cage comprising: a pair of rim sections anda plurality of pillar sections, wherein: the pair of rim sections has adiscontinuous incomplete ring shape, respectively having deficitsections, each at one portion, and the deficit sections of the rimsections are disposed coaxially in the axial direction so as to beopposed to each other with a predetermined clearance providedtherebetween in a state in which the deficit sections have the samephase in the circumferential direction; the plurality of pillar sectionsare used to connect the pair of rim sections and to separate the regionbetween the rim sections in the circumferential direction of the rimsections, thereby forming pockets for allowing rollers serving asrolling elements to be inserted and held rotatably; the pair of rimsections has thin sections being thin in the radial direction, thediameter of the inner circumferential sections of which is made largerthan that of the inner circumferential section of the pillar section,and also has thick sections being thick in the radial direction, thediameter of which is made smaller than that of the thin sections; andthe thin sections are disposed at portions positioned on the oppositeside of the deficit sections with respect to the center of the innercircumferential sections of the pair of rim sections.
 11. Thesingle-split cage according to claim 10, wherein the thin sections andthe thick sections, plural in number, are disposed alternately on theinner circumferential sections of each of the rim sections, and the thinsections and the thick sections are disposed while respectively havingthe same phase in the circumferential direction.
 12. The single-splitcage according to claim 11, wherein the boundaries of the thin sectionsand the thick sections adjacent to each other are positioned at portionsin which the pair of rim sections is connected by the pillar sections.13. The single-split cage according to claim 10, wherein the thinsections and the thick sections are formed continuously without stepssuch that the inner diameter is decreased gradually from the thinnestportions of the thin sections to the thickest portions of the thicksections.
 14. The single-split cage according to claim 10, wherein thesingle-split cage is equipped with an engagement mechanism in which thediameter of the pair of rim sections can be increased by expanding thedeficit sections and the diameter of the pair of rim sections can bemaintained constant by preventing the expansion of the deficit sections.15. A single-split cage comprising: a pair of rim sections and aplurality of pillar sections, wherein: the pair of rim sections has adiscontinuous incomplete ring shape, respectively having deficitsections, each at one portion, and the deficit sections of the rimsections are disposed coaxially in the axial direction so as to beopposed to each other with a predetermined clearance providedtherebetween in a state in which the deficit sections have the samephase in the circumferential direction; the plurality of pillar sectionsare used to connect the pair of rim sections and to separate the regionbetween the rim sections in the circumferential direction of the rimsections, thereby forming pockets for allowing rollers serving asrolling elements to be inserted and held rotatably; the pair of rimsections has thin sections being thin in the radial direction, thediameter of the outer circumferential sections of which is made smallerthan that of the outer circumferential section of the pillar section,and also has thick sections being thick in the radial direction, thediameter of which is made larger than that of the thin sections; and thethin sections are disposed at portions positioned on the opposite sideof the deficit sections with respect to the center of the outercircumferential sections of the pair of rim sections.
 16. Thesingle-split cage according to claim 15, wherein the innercircumferential sections of the pair of rim sections are made larger indiameter than the inner circumferential sections of the pillar sections,whereby the thin sections are made thinner than the thick sections onboth the outer diameter sides and the inner diameter sides in the radialdirection.
 17. The single-split cage according to claim 16, wherein theportions made thinner than the thick sections on the outer diametersides in the radial direction and the portions made thinner than thethick sections on the inner circumferential sides in the radialdirection are disposed in the same phase in the circumferentialdirection.
 18. The single-split cage according to claim 16, wherein theportions made thinner than the thick sections on the outer diametersides in the radial direction and the portions made thinner than thethick sections on the inner circumferential sides in the radialdirection are disposed in different phases in the circumferentialdirection.
 19. The single-split cage according to claim 15, wherein theboundaries of the thin sections and the thick sections are positioned atportions in which the pair of rim sections is connected by the pillarsections.
 20. A single-split cage equipped with: a pair of rim sectionsand a plurality of pillar sections, wherein the pair of rim sections hasa discontinuous incomplete ring shape, respectively having deficitsections, each at one portion, and the deficit sections of the rimsections are disposed coaxially in the axial direction so as to beopposed to each other with a predetermined clearance providedtherebetween in a state in which the deficit sections have the samephase in the circumferential direction, the plurality of pillar sectionsare used to connect the pair of rim sections and to separate the regionbetween the rim sections in the circumferential direction of the rimsections, thereby forming pockets for allowing rollers serving asrolling elements to be inserted and held rotatably, and the pair of rimsections are disposed so as to be opposed to each other in a state inwhich the centers of the inner circumferential sections thereof are madeeccentric with respect to the rotation axis of the cage to the oppositesides.
 21. The single-split cage according to claim 20, wherein the pairof rim sections has thin sections being thin in the radial direction,the diameter of the inner circumferential sections of which is madelarger than that of the inner circumferential sections of the pillarsections, and also has thick sections being thick in the radialdirection, the diameter of which is made smaller than that of the thinsections, the thin sections are disposed at portions positioned on theopposite side of the deficit sections with respect to the center of theinner circumferential sections of the pair of rim sections, and the thinsections and the thick sections are formed continuously without stepssuch that the inner diameter is decreased gradually from the thinnestportions of the thin sections to the thickest portions of the thicksections.
 22. The single-split cage according to claim 15, wherein thesingle-split cage is equipped with an engagement mechanism in which thediameter of the pair of rim sections can be increased by expanding thedeficit sections and the diameter of the pair of rim sections can bemaintained constant by preventing the expansion of the deficit sections.